I guess there are no readymade guides as such…you just have to understand the concept(read as much as you can) and then try on your own…ppl. are are ready to help you out if you encounter any issues while doing that…
the following links may help you with the concepts,give u references to how far people have managed to push the scores etc.
overclocking simplified:
Tech ARP - Newbie’s Guide To Overclocking
How to Overclock - Overclocking Tutorial
How to Overclock a PC - wikiHow
X-bit labs - CPU Overclocking Guide
for AMD X2s :
A Beginner’s Guide to Overclocking - techPowerUp! Forums
AMD Athlon X2 3600+ Overclock Overview, Page Three
PlanetAMD64 > Overclocking Brisbane 3600+