Four things to think about.
1. Type the address on an iPhone or Droid. How easy is it to punch in? Are there special characters? Do you need more than one keyboard?
2. Verbally tell a stranger to go to your domain. Can they understand the spelling?
3. This ties in with point 1 – How many words is your domain? As few characters as possible is best, but especially words. 2 longer words are better than 5 short words, assuming the character count is the same.
4. Is Google flooded with the keywords in your domain? What about making up a word. Therefor you already own the Google search for your name.
Update: See #5 in the comments.
6. Buy your own domain name! Never let a web design company or agency buy a domain for you. I’ve run into dozens of small businesses that have no idea where their domain was bought or who bought it. What happens if the domain expires? What happens if that agency goes out of business? Own your domain.
5. Set a time limit.
I’ve been sucked into optimizing domain names before breaking ground on a project – time that would be better spent building, writing, or thinking about something else. Whatever domain name gets picked can be changed. Sure, there will be challenges, but picking something that works and getting started can be the biggest benefit.
I should take that advice. I have an idea I want to execute on, but haven’t moved beyond the idea stage because the domains I wanted were taken.
A friend of mine was stuck in that same position. He ended up picking a ‘code name’ to build the project with. When it was time to launch, he knew enough about the market, audience, and customers to pick a great name.