First, read through the A64 OC'ing sticky. Then, after you read it, read it again
A few tips. Make sure the LDT multi is lowered to x4. Some boards will lower it automatically, but IMO it is best to set this manually to make sure. x4 is OK up to 250 "FSB" then will have to be lowered to x3 at 250+.
Take your RAM out of the equation at the beginning. Set a divider of 3:2 or 2:1 FSB:RAM. This may look like 133 or 266 for 3:2 or 100 or 200 for 2:1 in the BIOS depending on your board.
Once you figure out your max CPU OC, you can then apply a better divider to the RAM.
Lock PCI-e/AGP/PCI in BIOS.
Now that you have done that, you can start increasing FSB and increasing vcore as needed. Continue to monitor stability and temps.