During our first year at HBS, my classmates and I took  the opportunity to build cleverlayover, a flight search engine that uses advanced algorithms to find flights hundreds of dollars cheaper than any other search engine. We were able to acquire 20,000 users within the first month thanks to the diversity of skill-sets on the team.

Through the process, we tackled four challenges that every early stage startup will face. Here's how we approached each of them. 

1. Choosing a team

Choosing a team can be difficult because there are so many dimensions to consider. Some teams form around a specific skill-set to create a competitive advantage while others try to round out as many weaknesses as possible. Some form around friend groups, while others form around shared interests and commitment levels. Each of these formation criteria creates a different experience.

Our team came together because we had a shared passion for technology and building great user-focused products: four out of the six team members had cofounded their own company, three had worked in product development, and four were engineers. Everyone on the team was very analytically inclined, but we all brought a different secondary skill-set. The former venture capitalists had the pattern recognition needed for narrowing the ideation funnel while the serial entrepreneurs knew what it took to execute. The engineers built a great piece of technology while the award-winning photographer designed a compelling interface.

More importantly, though, we had all worked together in the past during various class exercises, and we knew we would have fun together. The various simulations and group projects at Harvard Business School provide a great opportunity for finding cofounders. We had seen each other's strengths and weaknesses and knew what we wanted to learn from one another through working as a team. 

2. Coming up with ideas

Coming up with ideas was more difficult than choosing a team--at first, we felt that every good idea had already been tried. However, we were able to create a spreadsheet of dozens of ideas, all of which we felt were viable and exciting, by treating every moment of the day as a brainstorming opportunity. In addition to white-boarding during in-person meetings, we maintained an on-going group text where we would jot down ideas as we went through our day-to-day lives. 

Often times, people keep notebooks to write down quick ideas, but they miss the opportunity to generate immediate discussion on those ideas. Through our group text, any idea that got introduced would be built upon on the spot, and the discussion would inspire new tangential ideas. 

Furthermore, we'd perform a regular evaluation of the ideas introduced to see if any of the business models could be applied to a different vertical. That allowed us to be exhaustive in our options and would also ensure that the best industry for the idea could be found--some business models required industries or customer segments with higher frequencies of transactions or larger transaction sizes to be viable. 

We came up with the idea for cleverlayover when we booked our own flights for the holiday season and realized so many inefficiencies existed in flight pricing. After experiencing travel with an additional layover and looking at the data to size the opportunity, we added it to our list.

3. Narrowing down the idea

Even more difficult than coming up with ideas was narrowing down the list. The prospect of committing to a single idea was terrifying, and even though the opportunity existed to pivot once or twice, we still felt limited in what we could explore.

Our process included several meetings to synthesize the ideas into four categories, three rounds of voting on the best categories, two prototypes to test out our favorite ideas and countless customer interviews to validate their viability. 

We applied our initial filter on not only the market size of each opportunity but also whether or not the products could be used in single-player mode--that is, users could find value from using the product even if they were the only person on the platform. We felt that generating enough liquidity for products that relied on network effects would require more than five months. This filter allowed us to narrow down the list of ideas to fewer than a dozen.

We also filtered the ideas by looking at our skill-sets to see where we could gain a competitive advantage. With an analytically strong team, we focused on ideas where we could acquire large amounts of data easily. Finally, we wanted to work on something we were passionate about since we would be spending the next five months, and possibly longer, dedicated to the company. Our most important filter was how excited we felt about the idea.

4. Acquiring the first thousand users

However, we soon realized that acquiring the first thousand users would be harder than choosing the idea. In the initial days when we just launched the product and had no users, we had to deal with the uncertainty of not having outside validation. We heard a great deal of negative feedback on why the idea wouldn't work and how many competitors existed. Based on the pushback we received from peers, we considered pivoting early. 

The only thing that kept us going was a conviction in ourselves and our idea. We redesigned features that confused users and changed the site's user experience based on the feedback we received. Gradually, people to whom we showed the site became more and more excited about the savings they could find. 

In the early days, we acquired users on a person-by-person basis. We would show the site to the person sitting next to us on a plane or waiting in line at a restaurant--places where people were trapped into uncomfortable conversations with strangers tended to be ideal. We'd show them the savings on flights and invited them to verify by looking at the bookings pages. We received the best reactions when people had just booked flights and now discovered that cleverlayover could have saved them a couple hundred dollars. They would go home to tell their friends and family about the product, and we'd acquire users gradually through word-of-mouth. We received our lucky break when friends kept telling people about our product, and word reached Conde Nast.

The journey so far on this early-stage startup has been incredible. We worked through some tough challenges, but the great part about a startup is that it never gets easier. Looking forward, there will always be more problems to solve and more opportunities to learn.