My guess is that you are using spray gloss in a can??

If you can - use the flat paint, it has less tendency to bleed. Also the flatter the base colour surface then the better adhesion you get from your mask edges.

But Marty is right - real thin later at first to seal the edges and then your top coat.

If you are spraying gloss enamel over an acrylic base coat then let it dry and the bleed can easily be removed with a razors edge - it just picks off. Then if you seal it with a clear acrylic or similar you have the same uniform finish to the whole job, plus it protects your work.

Bleed is really irritating! I have to deal with it more often than i would like