Stopping over run or bleeding (whatever you choose to call it) when using masking tape:
After masking, paint over the edges of the masking tape with the same colour (or Johnson's Klear) that has been masked over. Then paint the next, and different coat of paint over that. When the masking tape is removed, and if you've done it right, there shouldn't be anything other than a neat edge. You may also want to run a sharp knife along the edge of the masking tape before removing it.
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