Finding the right domain for your business is an important part of getting your website up and running. The most important point to remember: reserve a domain name before you start your business.
A domain name should have the following:
be short, to the point, easy to remember (eg. name of the business), avoid hyphens (makes it harder to type), match your domain with your brand you are selling, domain name should be as close as possible to the business name as possible.
These are only guidelines, and there are plenty of sites that generate multiple suggestions for a name that you might like.
.Com, .org, .net etc
There is no fixed rule for choosing a domain name suffix. However choosing a domain ending that either fits the country or the business area that you are in, is a good idea.