Normally I do headbox first (its easy), then front, then sides.
Some decals you need to do front first, then line up the sides so the artwork matches.
One big help for the front is to make up a 'plug' for the coin door hole. Cut a piece of timber out that fits snugly in the hole, so that when you apply the decal it doesn't sag in the hole and cause all sorts of dramas
