The lean startup methodology took what they taught in MBA classes and turned it upside down, completely changing the way most of us thought about entrepreneurship. No longer was starting a business about projections and management titles. Instead, it changed into experiments and data.

While customer interviews are a big part of finding your value proposition, they also can be a perfect time to build leads. Just because you're still looking to find insights doesn't mean you should stop selling. With a little preparation, you can discover insights about your business model and score a sale. Here are some ways to do both.

Step 1: Once you identify their problem, dig deeper

It's essential that when you start interviewing customers, you don't have any loaded questions. You want the people you're interviewing to be completely open with you. Swaying or selling them too early will ruin the advice you need for your business. Often you can tell you're getting good data if your customers start getting emotional about the problem.

When you hear this, they've given you a path to future business. Once you identify the problem that's causing them stress, dig into the problem deeper. Start by asking what's been the cause of the problem, and ask them how much they are spending to fix the issue right now. Go into how much time they are spending trying to solve the problem. After a few minutes, they'll start spouting off valuable information.

This not only gives you information but also opens up your customers' minds about how important the problem is. No one typically takes the time to ask the questions you're asking, so many customers don't think of finding a solution. When you open up customers' minds about how big the obstacle is, they'll become more interested in what you're doing.

When we started Alumnify, we used this method to generate a bunch of early leads. Most times, I wouldn't even have to make a sale or pitch my company. Customers would just keep talking and eventually ask me if I had a solution. Whether they eventually became a sale or not, I still got great insights from them.

Step 2: Pitch a solution, even if you don't have one

After they've found the problem, this is where most entrepreneurs stop their customer interview. Happy with the data they gathered, they thank the person for his or her time and walk away.

When you do this, you miss a perfect opportunity to generate business. Here your customer is with a huge problem, and you're going to walk away? No. Instead, pitch a solution, even if it's off the top of your head. When I tell people this, they usually ask, "Why would I pitch a solution that I haven't built?" The answer is because you want to find out exactly what needs to be built to make revenue.

Next time you're in this situation, pitch them a hypothesis you have that you think will work and see how they respond. If they don't like it, awesome--you shouldn't build that. If they do like it, now you can ask them if they'd be interested in your showing them a demo in the future. If they answered yes to liking your solution, they'll almost always be open to seeing a demo. Now you know your customer's problem, and know at least one solution a customer would be interested in buying.

Step 3: Track results and close sales

Don't stop interviewing customers once you have one who you've sold your solution to. Instead, keep conducting interviews until you get to about 100 quality ones. Then look back at the interviews and see which was the most successful solution you pitched. What were customers willing to pay for?

Once you've looked at the data and you have enough customers to make it worthwhile, contact those customers. Schedule a demo in the future and build your minimum viable product in the meantime. While the product is being built, schedule more interviews. Next, build some quick mockups and start showing them around. This could also be a great time to raise early capital if you need to. Most entrepreneurs think you need a finished product to raise capital. False.

Investors will tell you that it's much better to have 10 customers lined up and no product than it is to have a finished product with no buyers. Most companies don't fail because they never get a product off the ground. They fail because they can't get sales.