Always paint the sides first, it has been my experience that if you use either the clear or white waterslides, if you have multiple colors in your image you are gonna use, the clear works best over the white, but let's say you want to do a red car with black flames or whatever, the white slide seems to show better. Also,if you cut the slide out a little narrow, or just shy of being the same width as your car, its easier to get the water bubbles out from under the slide. Also, if you don't get all the bubbles out, simply let the car catch some sun light and it will evaporate the rest of the bubbles.
