In general, you are going to want to bump the fsb little by little until you find the spot that it becomes unstable. At that point you can add more voltage(do not over do it.) or back the speed off a bit.
As you increase the fsb you will also be pushing the memory, so keep an eye on it. If the memory passes 592, you should loosen the timings to 9-9-9-24.
CPU's with unlocked multipliers are much more easy to overclock as you only push the cpu and not the memory/chipset as well. If you have an option for PCI-E speed, make sure you lock it to 100.
If it is a gateway, you may have no options for FSB ect.
Since the cpu is a 1333fsb model and not a 1066 model, I do not even think you can use the bsel mod on it.