First, you have to upgrade your CPU cooling(if you still have stock) to do any serious OC'ing,
good airflow & cooling are very important.
This is a good place to start: how to overclock C2Q quads & C2D duals.
I recommend a great site, where I'm also a member, it has all the information a novice overclocker needs to get started: Overclock.net - Overclocking.net
But, sadly the Q8200 isn't a such a great overclocker.