Wipe the camera down with alcohol wipes. Don't use alcohol on the mirror, it will turn blue.
Get a can of air n blow out the insides. Take off the view screen n blow it off, don't wash it or use alcohol on that either, it will turn white and the dirt will only get worse if you rub it with anything.
If the leatherete is looking drab, use some liquid shoe polish to boost it's appearance. A bit of buffing will make it look as good as new again.
Check the film gate for dirt n crud built up on teh rollers n guides. Wipe em down with alcohol.
Run a paper backing test roll of film through without the lens n see if the frames are transporting properly.
Once you're done, get out n shoot lots n lots of film so you spend the entire winter in the darkroom printing.
As for parts, check out KEH "as is" section and see if you can find another body for about $10.