From and article on WinningWP.com about getting the best domain name possible by Karol K, he provides 22 essentials tips to help those new to the industry. There's only one other tip I would add to this post, it's well worth it to buy a great domain name. Memorability and validity make your business standout. Not everyone can afford a million dollar domain, but there's a reason why they are worth those kind of numbers, specific site traffic and being the brand authority.
Remember you are building a brand when you build your website, and there's no point to building all your collateral advertising around a sub par domain name.