Get an old coke bottle and cut in half lengthways. Practice putting even fine layers on and try different pressures on compressor. Too much pressure or too close and you will get streaks.
As a rule of thumb always try and work at lower pressures if you can as it gives you more precision and neatness. Higher pressure gives better coverage, but needs to be applied from further away to avoid the streaks / paint runs.
Once you suss the pressure and the paint consistency you will be away
