If you are doing a two tone. Maybe something like this...
Spray the silver, then mask the line for the blue, before you spray the blue hit it with silver again. What this does is seal the tape line so the blue doesn't bleed, you could also use clear for this. A large portion of the time you end up with a ridge. I lightly sand that area with some 2000 before clear, and then pile on the clear after that to try and make the line disappear. That is one reason I like using 2 part automotive urethane, it is hard and sprays thicker than the duplicolor, so it hides those things a little better. That chevelle was done with all duplicolor paint, minus the purple pin stripe.