I don't do anything except clean/wipe the areas down with brake cleaner immediately before installing. Only do one area at a time. I.E. spray one area, then install, then spray the next area, then install.... etc. Also, use a cloth towel or something that won't leave lint on when wiping the cleaner off.
Then, get a spray bottle and mix 1 part alcohol and 3 parts water or 4 parts, not a big deal. Spray that on and place the graphics on lightly and then position the graphics where you want. Once positioned, squeegee the water from the center out. This will ensure you get all the bubbles out. Go slowly and work from the center out.
Keep a hair dryer close by, because if you have areas that are concave or curved, the graphics will likely bunch up in those areas. You can heat with the hair dryer and stretch it just enough to get the bunch out. Be careful, too much heat and it will get really soft.