there's no safe advice, every component is different, they are set to a standard clock setting because that's what the manufacturer believes to be safe. It's trial and error if you have a good cpu it will clock high, some will clock higher than others. some motherboards are good for overclocking some fail dreadfully with a mild overclock. the motherboard/ chipset is the most crucial part as this controls everything, that needs to speak to each other.
if you are not prepared to replace anything you break, don't bother trying. if you overclock slightly you wont see any difference if you overclock enough to make a difference watch your temps. you have probably voided your warrenty and almost certainly shortened the life of one or more components, this shouldn't matter as they will probably life well past their 'needs upgrade' date anyway.
get advice from motherboards forum, i overclock using multiplier and voltage settings only from bios, this is because my motherboard is built to overclock and auto compensates all ram timings, voltages etc. you can then tune the cores up seperatly with software from motherboard site.
things may seem fine, remember some games hate overclocked systems some don't.
run a thrash test like prime '95 to test temps watch it for the first 30 minutes and leave it at least overnight to test stability. many leave it running longer.
i do this because computers is my hobby, you will probably have some problems it's up to you, stable system that plays everything at full settings or a mildly faster short lived dead one!
know the risks make your choice.