i5 is painfully simple. Raise FSB, Raise volt when gets unstable. That is the very bare minimum you need to know. Things you need to look for when OCing an i5 is
BCLK
CPU Multi
VCore
DRAM Multi
DRAM Speed
It's best to have a "1:1" ratio between FSB (BCLK), CPU, and RAM. Not everyone has RAM speeds capable of this so it isn't always possible but that is why there are RAM dividers.
I like how everyone on air cooling has "55c load". Time to recheck those guys, my water is 50-55c load at 4.3ghz. Lowest I ever had on a lapped TRUE with dual Sythe Kaze Ultras was 65c load.