Toyota Tercel

I have a 92 Toyota Tercel, 5 speed. For quite awhile now it has been putting out some blue/white smoke when I first start the car, and when I sit after driving, like at a long light or a drive-thru window. A friend of mine said it sounds like the valve guide seals, does that sound right? It goes through oil rather quickly. I also have to change the spark plugs about every 3-4 months. My car starts running really rough and changing the plugs seems to fix that problem. Any help on this would be helpful, so I can at least know what I might have to get done to fix the problem.
June 22, 2007.

Blue smoke is oil, white is coolant. The blue could be valve seals, but the white is usually a head gasket.

Jun 22, 2007.
Mechanic recently " replaced exhaust valves" entailed: machine head; oil change; replace cat convert; head gasket set; air filter; timing belt; spark plugs; timing cover gasket; dist rotor; dist cap; spark plug wires; oxygen sensor; cat cat converter; ant coolant; oil filter/oil. $981.02. AND since I have had to add 10 quarts of oil, now the smoking is more consistent than it was when I was changing plugs every month, and recently radiator smoking. But my gas mileage did increase by 20mpg. I went from 17mpg to 37mpg, but your exact description was the problem I had with my 4 speed 1.5L / 1994 Tercel. I should have just pushed it off a mountain! : )

Nov 18, 2007.