the correct procedure is 1 Powerwash with TFR traffic film remover to remove all dirt and tree sap hire a polisher with Farecla mop head and buy some G6 cutting compund ,keep the mop head wet and apply some compoubd to the panels and start to polish up the panel being very careful on edges as well as anywhere there are changes of shape,the paint is always thin here ONce you have mopped the whole van to the best of your ability wash off all the compound as far as possible Now you will need to apply some 3M finesse-it ,again use the mop to go all over the van with this and bring out the shine once you have finished with this you need one final wash to get the compound and excess finesse out of the rubbers inside the door seals etc .once this done you n eed good quality Wax to go over the paint ,just basic good wax which doesnt have cutting compound in it as they use on new acrs voila job done!
"apply some 3M finesse-it ,again use the mop" stand well clear lol and don't forget to mask everything within 5 metre radius