Its not a question of what must you do, its what you want to achieve. All chips are different, for example the 955 has two steppings a C2 and a C3. The C3 OCs better than the C2 and the same goes the the D0 vs the C0 on the i7 920.
The first things you have to take into consideration is if you have adequate cooling. What are using? Air, Water, Phase, LN2 (I doubt your using LN2 but hey I am putting it out there ^_^.)
Buy some TIM (Thermal Electric Material.) AS5 is good but the 200 Hour cure time is annoying if you want to OC right away. Arctic cooling MX-2,3, or 4 is good, it doesn't have the cure times like AS5 and is theoretically the same in heat dissipation.
Rules of Thumb: I rather use bad TIM applied correctly then good TIM applied incorrectly.
No one can tell you how far you can push your system (unless we were physically there) but we can tell you some advice and helpful tips in aiding you to OC your system to a very substantial overclock.
Take a walk through your BIOS and learn them. Turn off everything you don't need, like C1E Support, Power On (Cool'nQuiet) and other things that are not necessary for overclocking.
*Overclocking* Find a sweet spot between VCore and Fequency and stress test till you crash. Its all about trial and error and it takes a lot of patience.
Let us know if you have anymore questions