Try getting a foam latex make up sponge, they are pretty good for this kind of thing and give a nice smooth finish. Just use it for laying down your base coat and doing larger areas, then as Ron says you can use a pait brush for detailing the piece. Hope this helps you out.
Both Cyberpred and I live by the sponge. You can too!!! lol
I like sponges for putting down paint because I can do very realistic mottling effects, thin layers of color wash, and cover large areas almost as quickly as an airbrush. Plus, like airbrushing, you do not end up with any brush strokes on your work.
I use different sizes of sponges for various applicatons. Small sponges for fine,tight touches. Large sponges for larger areas.