If you are painting a clear canopy use a transparent type paint on the inside only. Most clear canopies except Goldberg can be dyed using regular Rit dye that you can get at the grocery or fabric store. The length of time you leave it in the dye solution will determine the degree of transparency. Cowlings and other plastic or fiberglas parts should be well polished using 0000 steel wool or at most 1500 grit wet or dry sandpaper. This will leave almost invisible lines that give the article some "tooth" for the paint to adhere to. If your model is covered with Monokote you can get their paint in aerosol cans that will match the covering almost exactly. If you are using other covering material you will find that most of them also manufacture a matching paint system. It is sometimes a good idea to prime plastic or fiberglas. Let the primer dry thoroughly before you sand it. Again use the steel wool or very fine wet or dry sandpaper. When you think you have it polished or sanded to perfection, do it again. One of the most important part of the painting process is the use of a good tack rag. Turn it frequently to a clean area and when you are sure it has picked up all the dust, do it again.