Overclocking amd 3000+ 939?

hey im waiting to overclock my amd 3000+ 939 1.8ghz wondering would i be able to overclock it to 2.5ghz? my case cooling has 3 fans one at front blowing in one at side blowing in and at rear sucking the air out also using a thermaltak venus 12 heatsink fan and will the FSB and the core voltage the only thing ill need to change also how much mhz should i increase it by everytime