Well first you need to do your keyword research, and Adwords is a good place to start, you can also use compete.com to see what others in your niche are optimizing for. Another good if not the best is Wordtracker. There are plenty of tutorials on Adwords, and in this forum you can buy discounted accounts at 15% of the value, say you want to buy an account with $100 you can get it here for around $15, alternatively some hosting accounts when you sign up will give you free credit.
Hope this helps