Depending on what you're trying too paint (body parts etc...), and having gone through multiple attempts at paining my glass seat base this winter, I can tell you that the base coat is less important than the clear coat stages with a view to getting a professional job. In fact, I ended up with only one uniform base coat, and multiple coats of clear which were then progressively sanded (400 - 2500 grit) to get the pro finish.