OK, so I am a Trials rider with some experience of sticker/vinyl application as I have worked in the sign industry. I’ve also fitted a full graphic set to a 4RT.
Some tips.
Work in a dust free pet hair free environment as the static produced by removing the backing paper sucks any dirt out of the air.
Before you apply your new stickers create some central line datum points with a fine felt pen.
Warm up new graphics with a hair dryer, but not too much or it ends up in a floppy mess.
Have a friend help you, ready to lift off graphics if application goes wrong.
Do not use too much detergent in water, just enough to form a drip off of a pin into a pint will do, breaks surface tension. Apply water via a discarded domestic cleaner spray, you want a mist.
An item like a credit card is good to smooth out water and bubble, but sand the edge as they are sharp and scratch.
Good luck, it often ends in tears or a fight!