How often should I tune up?

Not sure the exact schedule for your make and model, but the good average prevenative maintinece shcedule is as follows: Every 3k or 3 months change oil and check (service) battery and check ALL fluids. Every 7500 miles, lubricate the chassis (i have never done this) and check all hoses exhaust and bla bla bla. Every 15k rotate tires check brakes inspect fuel system. Every 30k (or two years) replace air filter (i check more often and clean mine, K&N, but depends on road conditions) replace fuel filter, check drivebelt, change differential lube, service cooling system, inspect or replace PVC valve, replace spark plugs and inspect their wires and distributer cap. Its nice if your move half of these to the other year, and you only sevice the cooling system every 5 years if it is orange.