I’d highly recommend you spend a significant amount of time reading about search engines and Search Engine Optimisation. Being a web-based business you are likely to find that the majority of your traffic, and thus your revenue, comes from the search engines. It’s therefore vital to understand how the search engines work and how to ensure your site is given the best possible chance by them.
As Fortune Palace said, you can expect that a newly registered domain will not rank for anything competitive for some months – this is known as the ‘sandbox’. So be prepared to wait for good revenue to come in, or look out for existing sites for sale that can help you overcome this time-delay (with the obvious downside that you can’t necessarily get exactly the name you want.)