I often get clients coming to me that want to change their website completely, not only a new look, but a new url as well. I have no problem doing that, but it’s important to think about it first. How important is that new url you want to use?
If you have an existing site, it’s probably indexed in Google to some extent. Maybe you’ve been working hard at getting ranked at the top. That’s something you need to consider when you change your domain. You absolutely must put up a 301 redirect and you must expect that your ranking is going to drop, hopefully only slightly, for at least a short time.
Once you’re new url is in place, you should try to get all of your backlinks pointing to the new site. If you’ve joined a directory of some sort, have your website listed in your sig line of a forum, you’re email, a friend’s site that might be linking to yours, anywhere you can update the url, you must do that as soon as you can.
Just be patient and you’ll rebound.