Don't take it prior to the treatment. Or if you do, be sure to tell the person doing the work. But if you will take a couple of benadryl right after the session, and then sleep with your head elevated above your heart, you shouldn't have any real swelling. Keep the "goo" on your face after, eve though if is stcky. A&D ointment isn't very hi-tech, but it does a good job. So keep it moist.
Do not pick at scabs, even though everything in you desires to. Leave the scab on as long as it desires. IT will disconnect as your body is ready and the healing has progressed. This gives you an even, non-splotchy line. Picking at a scab can take the pigment off of a whole section. Even a great eye-liner job looks bad with a half inch missing off of one lid. As our parents used to say, just leave it alone. Give your body a little time to heal. You've spent the money on the work, you've gone through the pain. Now just Let your body do it's work. It will be fine.