Pine Grove, Calif, USA
Minimal masking should be near the last on your list of things to be concerned with on a job like this. Prime the body with a light color primer (use white or light gray). do all your filling and sanding until your can see no flaws while moving the body around in a bright light. Then shoot a final, light coat of primer to make all the places you may have sanded through to the fiberglass/whatever all the same color (the color of the primer). Now you can start the color coating by shooting the lightest color, in this case it appears to be white, first. Paint the entire heli with the white because other light colors (such as the orange) will look blotchy if their undercoat is not consistent (note that the first white coat will look blotchy if you didn't do the last step with the primer). Mask and continue with the next darker color until all the different colors have been shot. Check the instructions for whatever paint you are using because many paints have a minimum cure time before going to another coat or before masking. Finally, after all has cured, do a EASY wet sanding with 800 or 1200 paper being careful not to go through any color. Then apply the decals, stick on graphics, etc and then apply the clear coat. Resist the urge to fondle for a couple of days to allow all to properly cure. There is no easy or quick way to a really good paint job.The older I get, the fewer things seem worth waiting in line for.