Having painted a few 14 foot mesh antennas back in the days when some manufacturers did not paint their mesh, I can offer another trick: when trying to coat bare aluminum material, using a device such as a Wagner Power Painter
(for fast coverage of large areas) or a bottle with hand pump for small areas, and spray white vinegar onto the aluminum surface. Let it dry for typically 15-20 minutes, and the vinegar will have etched the surface of the aluminum, making it much easier for your primer coat of paint to adhere. Semi gloss enamel would be suggested in most situations, and color does make a difference when painting
solid antennas. As Pete said, he paints a dark color on Primestar type antennas to quicken the melting of snow. In hot climates, dark paint will have the negative effect of attracting a lot more sunlight to the antenna surface than is desirable, which is why you see mostly white or pastel colors on big prime focus solid antennas; to dissipate the sun's rays. White versus black paint even makes a huge difference in C-band weather covers. The typical black or gray cover increases the temperature inside the cover and heats up the electronics if not properly vented. In tropical regions we found that a combination of painting the cover white and venting the bottom along with running a muffin fan, made quick work of daytime overheating problems.
Applying the paint: small electric painters such as the Wagner are probably least costly, but you need to experiment for the proper mix of paint versus thinner. You cannot run paint through one of these small electric painters without diluting it with the recommended thinner. Many thinners are composed of Xylene.
It's best to experiment with different settings to see what works, while keeping the spray nozzles clean. Otherwise, use a compressor driven paint sprayer.