First decide how high you would like to go. I replaced stock cooling with
Thermaltake Big Typhoon
I then replaced the northbridge heatsink with
ZALMAN ZM-NB47J
After I flashed my bios to latest version - so F10 for you.
Then I used this guide:
Core2Duo Overclocking Guide v1.1
(It also has recommended aftermarket heatsinks for overclocking)
I simply followed all the steps for DS3 board and got my E6400 to
3400mhz. I have my MCH voltage at 1.40, and FSB voltage at 1.40 as well, VCore set at 1.375V in the BIOS (I recommend overclocking through the bios as opposed to the windows based EasyTune utility). My memory is running at 2.0V but I have PC5400(667mhz) overclocked to 850mhz. You will likely not require such high memory voltage and 1.9 could suffice.
I would recommend to overclock at all stock voltages and then as you encounter problems increase them and see if they help the overclock.
The lowest ram: cpu ratio DS3 has is 1:1 and I would recommend you set it to that. Since E4300 runs at 9x multiplier x 200FSB = 1800mhz, to get to 3400mhz, you'll need 378FSB (corresponds to 378x2 = 756mhz DDR2 ram = PC6050). Make sure your ram is capable of overclocking to 756mhz or is at least PC6400 stock.
For stability testing to stress out the cores I used
Orthos and run
Blend test for 24 hours. Download
Intel Thermal Analysis Tool to monitor your temperatures.
Sorry if any of this was confusing. Feel free to ask.