From experience, I have a couple of tips:
1. It is harder to OC using 8 GB than it is 4 GB, because it stresses the Northbridge. In the end, you'll get a much more stable OC from 4 GB.
2. In most AMD boards, the FSB clock cannot be unlinked from the RAM. However, I had the best success with my old rig by OCing using the FSB (locked multiplier) and setting the RAM divider lower.
3. If you clock your 1333 RAM at 1066, and increase the FSB, you can usually run the RAM with tighter timings, meaning better overall performance than running at 1333 and jacking up the CPU multiplier.
4. You may have to bump up the voltage on your NB, but be careful not to overvolt it. That voltage is applied directly to the Phenom's die, and it will increase the overall heat of the CPU quickly.
5. Try not to exceed the RAM's spec'd voltage. That means don't exceed the max voltage of the lowest voltage pair. You may not be able to get two different brands of memory to OC well if they have different max voltages. OCZ RAM can often take a higher voltage that some lower priced brands.
6. Phenoms are expensive. Just ask my wife.