Make it short, avoid dashes and numbers, make it pronounceable - or use dictionary words. And use Google... there are several nice articles about this topic, even to be found on this forum.
Beside what GreenT have mentioned, register your domain name with .com extension if possible. It's good for your own branding. - Dynashox -
.com, but if you want to make a company or something you may want to take the .net also so no one else can.