I use unbranded cheap airbrushes and are ok for my needs. I have a compressor with a 3l tank, essential for good results, on-demand compressors are difficult to use i found. I usually use a 0.3mm needle at 20psi. I use nothing but Tamiya acrylics with an airbrush, mainly for ease of cleaning the airbrush, I have not had good results with Humbrol acrylics. The most important issue is thinning the paint to the ideal consistance, I use tamiya thinners; it does take a while to get the right feel of dilution, something akin to semi or skimmed milk. There are some excellent tutorials on YT, but trial and error is the only way to learn.
I hope I'm not teaching you to suck eggs, but If your brush has a screw end in the handle this changes the length the trigger can be pulled back, the further back it travels the larger the spray area, also distance from workpiece will change the area covered. I still consider myself a beginner and have just sprayed the camo on my 1/35 AS90 howitzer and I was very happy the the precision I got by going in close and restricting the movement of the trigger.
For much larger areas I would used rattle cans, Tamiya has a good but limited range.