Keep your PC away from extreme heat and cold. Try to keep it in a stable atmosphere where harmful vibrations will not disturb the drives and circuitry. Temperature changes are also harmful. Another method of maintenance would be to call a technician or repair service to do the cleaning and maintenance for you. I'll be posting up some links to other related areas on the web soon. .
Time is money, efficiency is a great asset.
Preparation is the best course of action in prevention.