The Tech Report has published a guide for newbies on how to overclock your rig:
The most important ingredient in any overclocking endeavor is a good chip. If you're looking to exploit the "free" overclocking headroom made possible by binning, you're best off looking at lower speed grades. If you're after the maximum overclock, you'll probably want to pick the number of cores and the amount of cache that you want, and then select the lowest speed grade available with those characteristics. If you have a choice between chips with different front-side bus speeds, it's probably best to pick the chip with the lower default bus speed. A slower front-side bus can make life easier for the motherboard, and you may even be able to overclock the processor without pushing the board beyond its specifications.