Look for a guys videos on youtube by the name Barbetos Rex. His mixing and application techniques are very good or I wouldn't suggest him. And he has reviews on many kinds of paints and airbrushes , to include one much like yours ( it's a matter of finding that video, he has so many out there).
When I mix my paints it's by viscosity more than ratio. Some brands you can go by ratio but in most the thickness of the paint varies from color to color and viscosity covers that difference. Some paints like Createx or for instance when you use their additives will flow even if a bit thicker than my standard on visosity. Others just plain don't spray if too thick. Thinner is usually better fwiw. Especially with the .3 needle/nozzle.
I have a conventional airbrush much like the one mounted in your set and I on average use it with that front mac valve half open. In other words I screw it shut and open it about half it's travel distance to full open. Since I have other airbrushes that are long standing favorites, they get used more but when I use this one it's most often with the .3 tip ( this set contains a .2, .3 and .5 ). I use it for art work not models ( I've painted hummingbird floral scenes with that airbrush), though I could use it for models just as well. But for lacquers I prefer my Badger 200 with .25 tip. For primers and enamels I prefer my Paasche H, also for varnish coating my wife's acrylic art work. And day in and day out for acrylic color and for Createx 4030 intercoat or Createx 4050 clear coat I prefer my Paasche VL using the included side cup. But I've been airbrushing for 50 years, the collection of airbrushes represents collecting over time. We all started someplace with one airbrush.
What many people think is a clogged airbrush is often just tip dry, easily cured with a Q tip and solvent in a minute or less if you have it on hand. In acrylic painting I cured this by adding Liquitex retarder to my acrylic thinners, be that commercial or home brewed. Finally here is one video from the site I suggested, just click the link: https://youtu.be/nojG6cz_6sY ( you may have to wait a minute till you see the little box SKIP ADS. Then his video will start. The ads are the latest "advancement" in youtube anomalies lol.