Buy a gravity-feed, dual-action brush with a 0.3–0.35 mm nozzle. On a tight budget, the Master Airbrush G233 set genuinely sprays; the Iwata NEO CN adds trusted quality control for a little more; and the Iwata Eclipse HP-CS is the buy-once answer most hobbyists eventually land on.
You do not need a flagship brush. You need a reliable one, a compressor with a tank, and an afternoon of practicing on a spoon.
Go deeper in our airbrushes guides.