I just ordered new negative stripes and want to know the proper way of applying them without making a mess. On the site I am ordering from it says use soapy water and these are an adhesive backed stripe

The little bit of soap (like ivory liquid) in the spray water bottle lets the stripe slide into place. It is "banked" against a straight blue tape line applied to the very bottom of the fender/door/quarter panel. The adhesive on the back still works and "glues" the stripe in place when it dries. Squeegee the extra water out of the stripe and then after the drying process, simply peal the front paper from the stripe. Finally cut between the front and rear of the door with a razor blade and you are done.

Many thanks George. Just ordered a set.