To start, drop your voltage to the lowest setting recommended for your processor. Overclock a step at a time, until you get to a point that is unstable. Bump your voltage until it is stable, and then continue overclocking. Wash and repeat until you either reach your comfortable level of overclock (heat, speed, etc.), or you have reached the maximum recommended voltage for your processor. Over-voltage your CPU at your own risk, as this is probably one of the fastest ways to ruin your kit (overheating being another). If you do this,though, you get the best overclock for the lowest voltage possible for your kit.
I tend not to worry about RAM clocks until I have a stable CPU overclock. Starting out, I keep the timings to the speed recommended for the memory as purchased For instance, if I bought DDR3 1333 9-9-9-24 rated memory, then at a minimum, I expect that memory to run at that speed no matter what my CPU clock is set at. Once I achieve a stable CPU overclock, I will then try to overclock the memory.
Tricks to a good overclock:
1) Buy your kit accordingly. Sometimes the most expensive processors aren't necessarily the best for overclocking. The idea is to get the most bang for your buck, so going out there and buying a $1000 CPU is not nearly as good for overclocking as it is to buy a $200 CPU and get within 90% of the processing power of the $1000 part through overclocking. CPUs that have unlocked multipliers are expected to be overclocked, but sometimes you can get good results from CPUs that don't have unlocked multipliers, since they can be bought for a bit less money and you can still wrench the same kind of performance as you can from the more expensive part.
2) Splurge on good cooling. You don't have to watercool, since most processors do well on air cooling alone, but the great thing about watercooling is that you usually only have to make the big investment once and then just keep upgrading your kit accordingly.
3) Also, splurge on a good power supply. Why buy an expensive computer and stick it with a cheap power supply? Especially for overclockers where even slight fluctuations in voltages might make a world of difference, if you start with a solid base, you have a better chance of eeking out more performance.