I need help overclocking my prcoessor?

Its a its a intel c2q q6600 with a air cooled zalman cnps9500 LED heatsink. .. right now the FSB clock its at 267MHz the cooling is at 13% CPU core at 1.325v and CPU GTL Vref boost is at 0v .. i dont know much about overclocking so i just want to overclock it to as much as possible without risking to fry my cpu or anything im my computer... what do i change it to?