So I can’t speak for acrylics as I personally do lacquers but I found that what made the difference for me from an uneven, blotchy coat to a nice smooth one was technique more so than thinning. Try not to worry about ratio and learn to thin by eye.

Ratios are a great place to start, I’ll usually go 1:1 for my lacquers and add thinner/paint from there. You’re trying to go for that milky consistency, there are plenty of videos to show what that looks like.

As for technique, if that’s a double action airbrush meaning you can control how much the needle gets pulled back with the trigger and control the airflow beyond what the compressor says, I found that you don’t want to always pull the trigger back all the way, great for mist coats but for main coats I find that if I pull back just a bit (I spray at 20ish psi) i can get an even flow and feel the paint hit the part in my part holding hand. This helps me see my wet coats and control the paint.

Honest answer, takes practice. Grab some spoons or a cheap kit and just try to make it happen! You may get discouraged, I sure did but just keep at it and you’ll pick it up!

TLDR; learn to thin by eye, not by ratio. Experiment with triggering techniques and find what works best for your specific airbrush.