A founder's guide to GTM strategy: Getting your first 100 customers

You've built something promising. Early users seem excited. Investors are intrigued. But as you look toward scaling, a sobering reality emerges: According to CB Insights’ analysis of startup failures, 35 percent of startups fail because they build something without real market need; another 20 percent get outcompeted trying to reach customers. You don't want to be one of those statistics.

This guide won't give you platitudes like “know your audience.” Instead, it offers frameworks and tactical advice to validate your market, build your go-to-market (GTM) motion, and acquire your first 100 customers. Based on insights from successful founders and Mercury's experience helping early-stage companies scale, we'll explore what actually works when transitioning from nascent idea to sustainable growth.

As Mallory Contois, Head of Community at Mercury, says: “Some combination of luck, grit, skill, and timing separates companies that successfully acquire their first 100 customers from those that struggle.” Let’s break down how to put the odds in your favor.

The most common GTM mistake isn't choosing the wrong channels or hiring too early — it’s failing to properly validate your market before scaling.

“Not having enough, or the right, conversations with their customers is the biggest misstep we see with early-stage founders,” Contois says. “Your first job is to deeply understand your ideal customer profile (ICP) and how they relate to the problem you're solving.”

Validation, however, goes beyond casual conversations with friends or former colleagues. As Jarod Estacio, co-founder of Grid, points out, “Your first hundred customers, users, whatever it might be — you cannot count your friends in that.” Estacio emphasizes that friends aren’t valid test customers — they lack the objectivity and purchasing criteria of your actual target market.

The depth of validation matters more than you might expect, too. While many founders do a handful of interviews before building, Estacio took a more thorough approach: “We did mainly informal conversations with between 500 and 1,000 potential users” before fully committing to their direction.

But how do you approach validation systematically? Contois recommends an integrated approach that builds on established frameworks:

1. Start with problem discovery using elements of the Lean Startup methodology: Before building anything, conduct structured customer interviews focused on understanding pain points rather than pitching solutions.
2. Test market interest with minimal investment through smoke tests: Create a simple landing page describing your solution and measure willingness to engage — whether through email sign-ups, demo requests, or even pre-orders.
3. Evaluate fit across multiple dimensions inspired by Marc Andreessen's framework: Consider not just if your product solves a problem (problem-solution fit), but whether enough people care about that problem (market fit), if customers will pay enough (business model fit), and if your solution meaningfully outperforms alternatives (product-market fit).

What separates this approach from simply following individual frameworks is the focus on validation as an iterative cycle. Each method reinforces the others — customer interviews shape your landing page messaging, sign-up rates inform which problem areas to explore deeper, and this collective evidence helps you systematically evaluate all dimensions of fit before committing significant resources.

What separates effective validation from “validation theater” is asking genuine questions rather than seeking confirmation of your assumptions. As Harvard Business School professor Tom Eisenmann explains in his research on startup failures, many entrepreneurs who claim to embrace the lean startup canon simply launch minimum viable products (MVPs) without doing proper customer discovery first.

Eisenmann calls this a “false start” — entrepreneurs who are so eager to build that they skip the crucial step of validating that they're solving a real problem. Don't make this mistake. Talk to potential customers about their problems before pitching your solution.

Many founders can’t wait to hire a sales leader once they've built their product, but that approach can backfire. As one GTM expert, Cailen D'Sa, put it during a Mercury Expert Session: “I see a lot of founders say, ‘Hey, I don’t know how to do sales. I'm just gonna hire someone or hire a head of sales.’ Do not do that,” D’Sa says. “You need to become an expert because at some point when you hand the reins to somebody else, you're going to manage that person and you need to suss out the BS when they tell you why they're missing numbers. Otherwise, you're going to be ignorant or not be able to decipher what's true and what’s not in terms of what’s happening in the business.”

Why is this so important? Early sales conversations provide insights beyond just closing deals — they reveal customer response patterns, uncover unexpected objections, and help sharpen your pitch. These insights are invaluable for product development, marketing, and eventually scaling your sales function.

“It's critical that the founder leads GTM before handing it off to someone else,” Contois says. “GTM motions are some of the best ways to learn what's working and what isn’t. In addition, founder-led sales and marketing are hugely powerful when done well.”

Timing your first GTM hire correctly is tricky. Contois offers staged advice on GTM hiring:

“Start thinking about a GTM hire only after you've discovered your preferred approach as a founder. First, develop a clear point of view on which GTM motions show the most promise. Then, hire someone who specializes in those specific tactics — whether that's community-led growth or B2B enterprise direct sales.”

When you make that first GTM hire, be explicit about their role. Estacio warns that the biggest challenge with early GTM hires is not setting clear boundaries. As with any role in a fast-moving startup, early GTM employees often get pulled between closing deals and building systems, leading to confusion and burnout.

“Do you need someone who’s just closing deals, who will wake up every morning and call 40 people before the end of the day? Or are they going to take a step back, look at what you’ve been doing and audit your systems and your processes?” Estacio says. Defining those expectations upfront will save you headaches later.

Once you’ve validated your market and started making sales yourself, it’s time to think strategically about your growth channels. D’Sa identified four main growth channels:

1. Sales-led growth: Direct outreach, demos, and relationship building
2. Marketing-led growth: Content, events, and lead generation
3. Product-led growth: Self-service adoption, freemium models, and in-product expansion
4. Partnership-led growth: Integrations, referrals, and channel partnerships

“You want to aggressively test a few channels to see what works and what doesn't, and which ones lead to the best conversion rates,” D’Sa says. “I'm more mathematical to see like, okay, let's look at week over week to see if that channel is working, is something broken in our plumbing.”

Choosing the right channels hinges on a deep understanding of your ICP. “I think defining your ICP can be difficult,” Estacio says. “Again, if you're in Y Combinator, you have your first 10 customers usually teed up for you... but you might end up skipping the work of really identifying who your ICP is.”

This identification process isn’t just about demographics — it’s about understanding the customer journey and where they naturally discover solutions like yours. Do they attend industry conferences? Search for solutions online? Ask peers for recommendations?

For each potential channel, test deliberately before scaling. Contois recommends a Lean Startup approach here too — run small experiments, measure results, and iterate quickly. Don't try to pursue all channels simultaneously. Instead, pick one or two that align with your ICP and double down on what shows promise.

The right technology stack can make channel testing more efficient. For early-stage companies, consider tools like:

• Sales engagement platforms (Outreach, Apollo)
• Call recording software (Gong, Grain)
• Collaborative email (Front, Superhuman)
• Data enrichment (Clearbit, ZoomInfo)

These can help you test channels with minimal investment while collecting valuable data about what's working.

As you test channels and grow your user base, tracking the right metrics becomes crucial. But which metrics matter most changes as you scale.

“For us specifically, the North Star was daily active users,” Estacio says. He explained that investors don’t need or want to hear the day-to-day numbers, though they remain important for internal operations. “Over time monthly active users, quarterly users, your total user base, start to become more important.”

This evolution makes sense — as your company matures, investors and team members need different time horizons to evaluate progress. Early on, you're looking for signals that people are finding immediate value. Later, you're tracking retention and expansion to prove sustainability.

Estacio also notes that while metrics should evolve, focus remains critical: “The goalpost has to change. It should change, or else you're not maturing as a company. What's most important in my opinion is picking a metric and then you can work toward it. You're more than welcome in the future to pick another one.”

For most businesses, you’ll want to track metrics at each stage of your funnel. D’Sa recommended “ruthlessly prioritizing your funnel” by tracking:

• Marketing Qualified Leads (MQLs): Leads generated through marketing efforts
• Product Qualified Leads (PQLs): Users who engage meaningfully with your product
• Partner Qualified Leads: Prospects that come through partnerships
• Sales Generated Leads: Opportunities created through direct sales outreach

For each of these categories, track conversion rates, customer acquisition costs, and lifetime value. This data helps you determine where to focus your efforts as you scale.

One often overlooked metric is time — specifically, how long it takes to see results from different channels. Some channels, like content marketing, may take months to gain traction but deliver compounding returns over time. Others, like direct sales, can show faster results but may not scale as efficiently.

“Even knowing this, I fell into the trap of believing my intuition and then maybe being underweight on user or customer conversations,” Estacio says. The lesson echoes that earlier point about genuine validation: Data-driven insights should guide your decisions, not confirmation bias or assumptions about what should work.

Getting your first 100 customers isn't about following a universal playbook. It’s about systematic validation, founder-led experimentation, and data-driven iteration.

Contois says the founders who successfully acquire their first 100 customers share these key characteristics:

1. Nimble and resilient personalities
2. Experience learning from great leaders at successful companies
3. A clear, well-articulated vision for their market space
4. Solutions aligned with cultural or macroeconomic tailwinds
5. Excellence in communication and regular updates

When it comes to building your GTM strategy, keep these principles in mind:

• Start with deep customer discovery before launching your MVP
• Lead sales yourself until you've found repeatability (around $500K ARR)
• Choose channels based on your ICP, not just what worked for others
• Pick one primary success metric initially, but be ready to evolve as you scale
• Set clear boundaries when making your first GTM hire

Remember that GTM strategy isn't something you set once and forget — it’s an iterative process that will evolve as your company grows. The goal isn't perfection from day one, either, but learning quickly and adapting based on customer feedback.

As Estacio puts it: “You just pick a metric, build for it, optimize based on what your users or customers are telling you, and then move on to the next one.”

Check out our downloadable checklist to put your GTM plan in action.