First tip...
Make sure the sand paper is well soaked, i left them over nite.
Start off with the finest Wet and Dry you can find, i started with 1200, it was little too course for some of the panels, but i went with 2000 grit in the end
Do a test first, don't rub the whole car down thinking it will be fine, if you go thin you'll be screwed! do somewhere concealed like door jam, normally the paint is thick enough so you can trial and error.
I would advise you have some serious level of paitence, this whole saga took me 2wks to complete due to poor british weather.