You can get pretty good results from brush painting, althought some effects would be hard to achieve such as Luftwaffe mottles and soft edge camoflague demarcations. Some techniques you can try is to use a pretty broad brush with really wet paint and only brush stroke it in one directions. Once the paint starts to level stop brushing or else you will end up with some heavy brush marks. After the paint has fully dried and cured, you can wet sand with very fine sandpaper to get out even more of the brush marks. Works very well, for US Army Air Force schemes and similar schemes.