heres a few
dont over rev a 4 stroke (aka prop it correctly) the valves will "float" and hit the piston resulting in a new engine comming in the mail from tower
4 strokes can chuck the prop when they are too lean (causeing a backfire), dont stand in front of the engine during tuneing and always double nut it.
set 4 strokes slightly richer than 2 strokes they have more moving parts

as for props try a 13x6

plan on checking the valve clearence after 5ish tanks