Welcome to the forum and to airbrushing!
Airbrushing is a wonderful experience, but it requires something very important: Practice, practice, practice.
The reason is it has an overwhelming amount of little different variables and all can affect the experience. It can be frustrating at the beginning, but it is part of the learning curve.
There are millions of tutorials on Youtube. However, use those as a general guidance and starting point. There is no absolute truth as the setup that may work for person A may not work for person B.
It is very important you get acquainted with your equipment. A big mistake is to try a new airbrush, get less than stellar results the first time, blame the airbrush and get a more expensive one only to get even worst results. You need to know your airbrush and get familiar with its personality. That is one of the many variables I mentioned. You want to lock some of those variables to make sure you learn what affects what.
In the same line, there are tons of options for paint types. Water based, solvent based, acrylics, inks, dyes, enamels, lacquers, latex, urethanes and many more. Then multiple brands for each. Choose one and stay with it until you master it. That's another variable you want to lock until you have more experience.
A dirty airbrush is a recipe for frustration. A clean airbrush is key to success.
You mentioned car models. That's what I've been airbrushing for 30 years. If you have any specific question or if I can be of any help please let me know. This forum is a great place as everybody is willing to help.
The most important part is: HAVE FUN!
**EDIT** By the way, I can barely draw a straight line with a ruler...
Thanks,
Ismael