Techniques... A damn good heatsink/fan setup. A case that provides a lot of airflow...
As far as overclocking, it is a lot of trial and error. A fair amount of BSOD, restarting and retweaking the BIOS.
Adjust one parameter at a time. I can't stress that fact enough. If you start tweaking all sorts of stuff at once, you won't have a good grasp of what worked, and what it was that gave you the BSOD.
As you require more from the proc, you need to increase it's voltage,, but by absolute minimal amounts. Do it in small incriments.
Same goes for your memory.
Make sure that if your northbridge and FSB are strapped together, you unstrap them.
I had best luck keeping my FSB at a number that matched what the memory freq was, and adjusted the multiplier.
I know it sounds like a rediculous process, but I know what I am talking about. I have a 1.8ghz proc OC'd to 3.6ghz, on air cooling, never breaking 49ºC. I have been running it stable for just under two years at 100% overclock. It has been documented here as well as on OC forums.
Here is the thread on my OC. I had it at 3.5, and after a few days of tweaking, got it to run stable at 3.6ghz.
zerothread?id=314042
The thread on the OC forums is probably more in detail. I don't really remember, and don't care to go find it.