There are some points you have to care about  when you are planning to register a domain.

1- Choose a good registrare (a company where you will register your domain with) .
2- Try to get .com domain if it's possible.
3- Try to make your domain name short and simple as possible as you can .
4- Try to make your Domain name  easy to spell .
5-  Try to make Your Domain name easy to remember for your site visitor .
6- Try to make your domain name give your site visitor an idea about what is your site about .

I will try to explain these points in next articles I will add in This site .