Hypebot posted a nice article with three tips about your own domain. Good tips. But I want to add two more tips that I think are even more important and come from my personal experience working with many clients.
1. Auto Renew – Set your domain to auto renew. Just do it! I promise you will not be sorry. This means that when your domain expires it will automatically be renewed, with no interruptions. I have had too many experiences with clients, large and small, who did not auto renew their domain and did not notice the emails being sent to them to alert them to the need to renew. One day somebody notices the website is down and the panic begins. The scramble begins to quickly get the domain renewed and back online, in the meantime your site is down and often replaced with a generic page. This leads into tip number two.