To overclock or not to overclock?

I just got in my XFX HD 5770 video card in cause my 4870 fried only after 1 year and a half.

I have never overclocked but im interested into what big of a difference it really makes.

Also how is the safest way to overclock in ATI Overdrive?

Do I have to go up in incriments or just set the clock speeds I want?

Always go up in small increments. Use furmark to stress test for artifacts and watch your temperature. Heat is pretty much your biggest enemy. I don't think you'll have to worry about frying your card unless you do a volt mod, but as I said before just watch your temperature.

Go up small increments and use Furmark for stability, and also consider using unigene for a long period of time to check for artifacts. Also you should play a graphic demanding game to check for both. Thats how i check my overclocks.