Just kidding!!

Buy a can of spray rust inhibitor like JP Weigle's Frame Saver, or RustCheck, or Boeshield T-9, and spray it down the seat tube, head tube, and into any small holes you see in the stays and forks...but while that is the best way I did it an easier way and never used the spray stuff and never had rust issues, but combine both of these things and the bike will outlast your grandchildrens lives!! The simplest things to do is to put a light coat of grease on the seat post and the inside of the seat tube and after reinserting the post wipe off any ooze. Do the same thing with the stem. Next buy a Lizard Skin headset seal protector, it wraps around the lower headset keeping muck out of the headset. Do not use WD40 to spray into the frame, it will not work at preventing rust, it will displace water so if you get water in the frame you can spray the frame with WD40 once you drained it out, wait a couple of days and then spray the rust saver products I mentioned.

Anytime you find a scratch that goes to bare metal quickly touch it up with paint, usually fingernail polish or Testors model paint will have a color that matches.

Wax your bike with a good automotive wax like Mequiar's Ultimate Liquid Polish or NXT Generation Tech liquid, or Mothers Reflection or California Gold Synwax Liquid, either of those two brands are the best just use whatever you prefer, I prefer Mequiar's Ultimate for dark colors especially black. Anyway just wax the bike gently, no need to scrub hard, and apply twice a year. If you use any other wax then mentioned you'll need to pay real close attention to make sure the wax contains NO cleaning or compound agents that are design to remove swirl marks or restore faded color etc because those remove a thin layer of paint and constant use of that sort of product will ruin a bicycles paint job and destroy decals, so always use non-abrasive.