Hi Mike,
You said: "I actually feel rather stupid because I have a degree in IT."
No reason to feel stupid - IT and IM (Internet Marketing) are 2 completely different animals. If you want totally free traffic then brushing up on natural search would be the way to go. If your topics are true niches that don't have lots of competition it's not that hard to get top rankings.
Bruce Clay has lots of good do it yourself SEO info:
http://www.bruceclay.com/web_rank.htm
Hope that helps just for starters. Anyone else want to add some tips?