AN answer depends on alot of variables.
For example, what hardware are you using? (motherboard,cpu,ram,heatsink,etc)
What are your goals? (computer uses, clock increases, etc)
YOu have to provide some more details because everything is different depends on the situation. If you only looking for a slight overclock you'll be fine on auto, but you need to have a good cooling solution, a cpu that can handle it (which most all cpuscan take at least a 20% OC now a days), a decent motherboard, some good ram, blah blah blah...
Details, details, details please