I always say the same speech.
You should start reading a lot, and by this I mean, try to google or look at the forum for the basics of overclocking, the general stuff, then move to some reads of logs/tutorials of overclocks on the same setup you have or similar ones (for example, same mobo with another CPU, or another mobo with the same chipset overclocking the same CPU you have).
Then you could make use of one of the most popular techniques: raise your voltages to the safe limit and apply the CPU core you which to achieve. After that start reducing every voltage you raised until you find the minimum necessary for stability.
And for buying a new computer, do what I did on my first time: read everything about CPU, then choose a CPU. All about RAM, then choose RAM. Mobo, then choose mobo, etc, etc, etc
Welcome to the forum, you have come to the right place.