Your domain name is your real estate address on the Internet. Yahoo!, Google, MSN, YouTube, and the rest, have all carved out their namespaces and their brand names are radiant as ever. The choice of a domain name is not any more complex than the choice of a name for your product or your new business. As such, these general thumb rules should be followed so that life can be happy both for you and your intended audience.
i. Shortest names hit home more quickly. They are fun to type, impress on human memory quite efficiently, easy to fit into social feeds (like Twitter, BlackBerry statuses), and fit well in the word-of-mouth marketing channel.
ii. Let your business name and your website name mirror each other. Case study: LiveSpring Media is a company that provides website consultancy. For their domain, "webconsultants.com" wouldn't be a bad brand name, but for a domain name it could be a bad choice. Why? Because LiveSpring media is the brand name that they use to market themselves. Persons in search of their website would be confused now, because they would by default, associate livespringmedia.com with Live Spring Media. To prevent all of this, one should consider their website as part of their biz plan.
iii. Be careful not to infringe on copyright. If you are running a used car dealership company for Toyota cars, check with Toyota first if you are planning to include their name in your domain.
iv. Choose a .com over a .net/.org. Unless you definitely plan to run a charity organisation (for .org domains) or a network (for .net domains), always stick to .com domains. They have the highest values in the Internet market, and humans tend to think .com first if for some reason they didn't hear your domain name properly. Not many would try a .net or a .org if the .com fails - only the techie ones.
Buying the Name
First you need to check if the name is available. You can do this with the tool below. Simply type the domain name you are interested in a press enter.
Several companies around the web sell domain names at various different prices. They all come with different interaces for management of your domain name, and some make it hard for you when you are ready to switch or if you want certain custom features. NameCheap.com is a good service to use. You can also consider LiveSpring if you want quick setup and extensive support. You would choose the latter to save you the hassle of going through the process of securing your domain yourself.