After every run I give my car a good blow out with compressed air to get the loose stuff off, then blast the whole thing, motor and all, with a can of contact cleaner and go over all the hard to reach places with a fine artists paintbrush (the little pencil ones) to get the last of it off, and of course just do a general check of the car for belt tension, any loose, broken or binding parts, dodgy connectors etc, and chuck it back on the shelf out of the way. For the bodies I use compressed air, then dab it with a damp flanellette cloth to remove the finer dirt, then wipe with a dry flanellete with a little Tamiya Polycarb cleaner on it, when doing your bodies use a soft cloth like this otherwise you WILL put swirls and scratches in the lexan, which dulls them pretty fast.
Once a month I pull the car down, go over the compressed air and contact cleaner routine on each part of the car, pull my diffs (mostly on my racecar but if i use them on my drifter i do this as well) down, soak the balls in Brakeleen, CO cleaner the pulleys and halfshafts, clean and check the screws and nuts as well as the stainless washers in the diffs, then reasemmble with a fresh tube of ball diff grease and set to my liking. Lay all the bearings out in a tray and blast them down with air and contact spray, give them a scrub with an old toothbrush, and soak them in a clean tray of PTFE dry lube so they dont attract all the shit off the ground when they're on the car, and obviously bin and replace any rough or seized bearings, like to do a full replacement of my bearings at LEAST once a year. Other than that everything carbon and alloy is CO cleaned, left to dry and wiped down, anti wear grease applied to CVD's as well as a dab on contact points like roll pins (suspension arms), re-loctite any important screws, reassemble and go out and thrash it all over again
You dont have to be quite that fussy and no doubt other people will have their own opinions of whats right and wrong with how I do it, but its worked well enough for me over the last few years with all my cars needing nothing more than routine maintenance and the odd broken arm/dogbone/hub carrier replaced over the years as well as consumables like bearings. Couple of hours spent once a month can save you quite a bit of coin and you'll find yourself getting much faster at pulling your car down, meaning you'll be able to fix problems quicker too. Invest in some entry level RC tools (i've had Himoto ones for a year and they've been great) to get you on your way and a workstand, as well as empty takeaway tubs for keeping your stuff together when cleaning and rebuilding. Have fun