Set the miter saw up on a table or other stable foundation.
Measure the crown molding and mark with a pencil at the desired place for the angle to be cut.
Line the crown molding up by propping it against the fence where the cut is to be made. Then set the blade to the desired miter angle.
Turn on the saw and pull down on the handle so the blade goes completely through the molding, while keeping a hand firmly on the molding so it does not move. Let go of the handle once finished and the saw blade will stop.