You have to watch several things. Computers are not as simple as they once were. Make sure your CPU voltages are right, your cards are fully seated, CPU is installed correctly etc... If you're not sure about something, ask specific questions. (General questions are hard to answer.)
I always keep the palm of my left hand resting on the frame of the box so that everything I touch is at the same potential (and I don't walk bare-footed on wool carpet holding my cat just before I decide to play with the innards of my pc). Get a small magnetic philips screwdriver (so the little bastard screws don't get away from you). Blow everything off with one of those cans of air (read the label, it ain't actually air but a hydrocarbon - no smoking, no open flames -- but they do help starting the logs in your fireplace, though a dixie cup of sawdust and candle wax works better and cheaper).
I am rambling again, time to log off and get some food