Going in 'baby steps' is a VERY good idea, you can find the point where the CPU starts to glitch, then step it back a little to that 'sweet spot' where it will run nicely.
If you are going to overclock on a permanent basis, keeping the CPU cool is key.
Spending some $$ on enhancing your cooling could save you some grief down the road.
For really aggressive OC's, water cooling is the way to go, but keep in mind that is 'advanced' tech, despite there being water cooling kits out there that pretty much anyone can set up if they have half a brain.
Yes, OC'ing a CPU will shorten it's lifespan, but I don't think anyone has managed to figure out by how much.
The above things are what I know to be true.
I have OC'd a CPU before (a looong time ago) and managed to get away with not blowing it up, a big electrical spike took care of that later. :p
