For best results, "Jamb" all the panels off the car, do not paint the outside, just all the edges. Re-assemble the car, mask off your freshly painted jambs, then paint the body. Good luck...
I agree. You'll want to commit hari-kari if you paint the panels off the car, then accidentally nick the paint during reassembly. And shooting the paint with panels on the car eliminates any continuity or metallic flip issues from panel to panel.