Do Not Cheat. Period.

If you walked into a room full of genius scientists with PHDs, do you think you could outsmart them all? No. Google has hundreds of rooms full of genius scientists with PHDs, and their job is to work 60 hours a week to make sure you can’t fool Google. You can’t outsmart them. Ever. Ignore any advice on trying to cheat the system and focus on making great web sites with great content, and your sites will show up fine in searches.
Rule One: Stick to Your Keywords