The google keyword tool is an awsome tool for finding the right keywords for your project. I like Google adsense because it kinda has a built in keyword integrity tool. Google will notify you if there are words that can better your project. It also shows how many domestic and global searches each word recieves. You want to use words with the highest search capability. Keep in mind that you do not want to use to many common and basic words in your keywords. For example, if you were to advertise a travel site, you don't want to use cheap hotels or hotels, etc. Instead, try using words like hotels in Europe or Last minute hotels in Hunan.