1) Prime it.
2) You should use the same brand and same type through out the paint. In this case, you need to use HoK primer, Basecoat, and clear coat among other products.
3) Laquer thinner should work, that is if you use an acrylic-laquer paint.
4)HoK Clear Coat
OTHER:
Use a high quality airbrush, HoK can ruin a low quality airbrush. If you need anything else ask, I am a professional automotive painter.