If you really don't know what you're doing, I guess the worse thing that will happen will be that you have an unstable system.
As for the activity itself, I would say building a computer would be the tough part of overclocking, and that's as easy as putting together some simple Legos.
After that free Mhz are just a few BIOS/Jumper settings away. Take small steps, run Prime95 for a while at each step. If it is stable, you can move up in speed. Small jumps in speed usually don't require any increase in the voltage to the chip. And you usually have to increase the voltage rather rapidly for any speed increase once you hit that "stock-voltage wall".
Other parts of overclocking should be part of normal computer maintence. Like making sure temps aren't too high, keeping your case clean and occasionally stressing your system to make sure it is completely stable(<shameless plug>or by doing a Distributed Computing project you could do that all the time, Go TeAm!!!</shameless plug>). These issues basically stem from the increase in heat production by basically every overclocked component in your system.
So.. in fewer words, overclocking does not entail certain disadvantages beyond those of normal computer use(for someone anal like myself anyway, not the average "Dude you got a Dell!" person).
Defter ---- Asking why am I up so late and typing on the computer???