How can I improve my business?

Customers, Customers, Customers. Try to find out why people are buying or not buying your product.
Try not to tinker too much without having a really good idea of what people want.

e.g. Try not to waste time building something which you think people will buy, or you think is cool.
Spend time building a minimal viable product and see how your customers react and use their feedback to advance and tune your product.

A good book to read is "the lean startup". Really helps people understand how to focus your efforts in a startup like environment.

Without knowing what business you're doing and how far you've come with testing customer adoptions/traction, I would recommend reading The Purple Cow by Seth Godin. A really easy read and the book will make you test your product's ability to do something different and will help you evaluate whether your product has the potential to solve a true customer need.

This depends a lot on what your business is exactly. The main piece of advice that I would give is to talk to your customers. Ask them how they found out about your business, and why they chose to buy from you. Were they happy with their purchase? Would they recommend your business to their friends? What would they improve about your business? Write down a few questions like this, and any others that you can think of that might help you understand how your customers see your business.

Your first customers can become your first allies in growing your business. People like to be "in the know", and many of them may want to show their friends how cool they are by introducing them to this "cool little start up that I came across". You can give your first customers extra benefits for showing their friends your business - even something small like "I'll give you a sticker for every friend that you tell about my business" can help out a lot.

Befriend your first customers, make them feel special, thank them for choosing your business, and give them a great value and they will help you.