Many entrepreneurs get disheartened when a customer refuses to buy from them. However, as a famous book advises, the sale begins after the customer says No!

Customers have multiple reasons for rejecting you, so don't take this personally. Sometimes the features your product offers may not be good enough; or you may be too expensive; or they may feel that you will not be around for long enough for them to take a risk on buying your product, because you may not be able to support it if you go belly up.

Many entrepreneurs give up when the customer says no, and they complain that they wasted many months trying to pitch and adding as many features as the customer demanded in their attempts to delight him. When they find they are not able to close the order in spite of all their efforts, they start feeling sorry for themselves and blame the system for being start-up unfriendly.

Yes, it's true that life is unfair, but just because a customer says no it doesn't mean you need to give up on him. The secret is to keep in touch, and continue showing them that you are making progress. Thus, if they wanted three additional features that you weren't able to provide, show them that you are working towards adding these to your product, so that you can meet their requirements - maybe if not now, then in the next two months. This will signal that you value their business and are working hard to win it. This will help you to earn their respect and they will be more willing to treat you like a potential business. They can see that not only are you making the effort, you're also willing to be open and transparent by sharing share what you're doing , and demonstrating the progress which you're making in order to with their business.

More importantly, it will allow you to retain your position in their share of mind, so they will consider you as a serious contender when they finally place their order. This way you're much less likely to lose the deal to a competitor! If you sulk and just give up, they will assume you're no longer interested, and will buy from someone else. 

Yes, you have to be careful that you do this for serious customers only - those who have the need and the capacity to pay - don't waste your time on guys who just want to kick the tyres!