Honestly, I would find a really really cheap bike similar to it and practice on that. It really depends on condition as to whether or not you need to completely tear it down or just to a light rehab and enjoy it. You don't want to get bogged down in a major overhaul just to lose interest and never ride it.

Key points?

Brakes. If this is a keeper, find yourself some nice new pads and try out the cables. If they are nice and free and look ok, then leave them. If they show resistance, replace them. Take the brakes apart and clean and lube the moving parts, really depends on the kind of brakes as to how you do this and how much you lube.

Next is wheel truing...you'll need a spoke tool for that and if you've never done it before there are lots of articles and videos to show you how. Just remember to do little movements to make your wheel really straight. I do this after the brakes as they usually give me more of a hard time and once the wheel's are trued, it doesn't take much to realign them again, just a quirk I have.

Wheel bearings: Clean everything (from the little balls and races) and repack them with grease. Tighten to the point where there is no play in the bearing but its not tight...sort of magic trick to get it right, but keep doing it until you think you've nailed it. It's a pretty narrow span between too loose and too tight.

Finally...drivetrain. Chain and derailers if it has them. I'd replace the chain if there is any sign of wear or excessive rust on a keeper bike. Lightly oil the rest, the rear derailer has those little idler wheels that love to be greased now and then. You'll need to align/adjust things for sure, once again, the internet has you covered for that.

On keeper bikes, I replace things as original doesn't really matter too much on things like chains and cables. On bikes I sell, I tend to rehab them...takes more time but to take something that didn't work and make it work feels nice.