Overclocking Basics and Temperature Guide
We have a guide on this. it is a bit dated, but the basics are the same.
There are two main schools of thought to overclocking.
The first is to raise your fsb and stress test. if it is unstable then raise your voltage to match. Rinse and repeat.
The second is to raise your cpu voltage to the max safe and keep raising the fsb until it is unstable. Then you lower to the max stable and sit there.
Either works. it comes down to a preference thing.
Some considerations, always keep and eye on your voltages. 65nm chips are rated for 1.5v and 45nm are rated for about 1.3v max. Although for benchmarking runs you can go higher, it is recommended to never run the chips over the max safe 24/7.
Also keep an eye on your ram, your memory speed is directly related to your fsb speed, and generally your ram cant oc as high as your fsb can, so if you may become unstable by pushing your ram to hard. What I normally do is set my memory divider really low like DDR2 800 for my DDR2 1100 sticks, and then when I get my cpu where I want it I bring my memory back up to speed. Good memory can overclock too, and of course voltage always helps but I would OC the cpu first and then worry about memory, that way you aren't trying to figure out what has got you unstable.
The next thing in order of important is your north bridge voltage. In an air cooled co you may touch this once or twice. When I hit 4.1ghz on my e7200 my NB was only 2 notches above stock. Nothing major but the higher you go the more that will become an issue.
And as always look at your temps! over 60c is getting too hot. I like to keep my idle under 50 if at all possible. That isn't to hard for me though, I have a core contact freezer.
I hope that helps, and as always good luck!