I've done 3 vans and it's really easy.
The logos etc are supplied on squared off backing paper so its only a case of eying it up level on the van then stick a piece of tape on each corner. Once happy put a long piece of tape vertical down the middle and take off the 4 corner pieces. You now have the vinyl secured down the middle. Pull of the backing on one side of the tape line pull it tight and apply, a cloth, a sponge anything will do. Then pull off the tape and apply the other side.
Lettering you'll struggle to get bubbles, bigger images you might but just pop them out, you won't notice them unless you are really inspecting