I second Ego. If you're going to use AdWords (it's certainly viable and, if your site content is good, has a very attractive ROI), set up Google Analytics on your site first.
It's free, and it will show you everything a person does when they visit your site. For example, it will tell you how many hit your home page and then leave, how many click through to different pages, which pages have a high conversion and which don't, etc.
This is a great, great tool for analyzing where your site is strong and weak. The Analytics website also has a lot of great, free info on constructing your site in a way that will help you achieve the goals you want to hit.