The best experience I've had over the years with OC'ing is moving it up in the smallest increments allowed by the BIOS and with each bump, test as thoroughly as you can. When you get too high, it'll let you know with a BSOD. (In my experience which includes gaming since 1996)
Disclaimer:
As with any tweaks, to any computer, especially OC'ing, you are responsible for any damage done. Unless the manufacturer encourages OC'ing, and explicitly says so in their warranty docs, it can void your warranty.