You are wise to ask.
The most important thing is to not use any cleaners that cause hydrogen embrittlement. Any cleaner that has anything "cloride" or "flouride" in it will cause the aluminum to loose electrons and become more brittle. This is especially the case for bare aluminum such as leading edges of propellers and rotor blades.
That means no simple green, 409, or anything else that has "cloride" or "flouride" in its ingredient list.
I have used bug and tar remover for bugs but I'm sure some on here will say that its too harsh.
Make sure it is cool before starting, at least in the engine area. Spraying the exhaust while it is still warm can cause cracks.
The paint is not base-coat clear-coat. Its a single layer, no rubbing compound.
I'm not sure about waxing. I know it can be done but not sure what to use.
Start with a wash like you would a car with basic car wash soap and water and brush very lightly with a soft brush. Then use aircraft grade cleaners such as 210 on the windows, not windex! And use only new microfiber towels on the windows, they scratch easily, no paper.
Remove any remaining soot with an aircraft grade soot remover such as aeroglaze or Brulin 815MX (follow directions for dilution and rinse)
Unless its a vintage aircraft, the bearings will all be sealed and the electronics waterproof, so there aren't any areas you cant spray. I would ask the owner to be sure on that one though.