Firstly, you should find a domain registrar to open an account with. .com, .org and .net extension are the most reputable. A short, descriptive and memorable domain may just be immense profit in your hands. Secondly, the domain should describe your product, brand, or service, so to say, the content of your website.
Thirdly, you should increase the page rank of your site to get more traffic in your site.
Good luck!