I forgot I had one of these years ago before I really got back into building. Got it more for doing sons pinewood derby car.

There are so many variables for thinning paints for airbrushing. For instance Iawata NEO and Eclipse you don't always need to thin at all. I have a Neo and it sprays Tamiya, Vallejo, and Model Master with no thinning, straight from the bottles. Most others brands you will need to thin and each may act a little differently. I've heard consistency of both skim and whole milk. I can't recall how much I had to thin with that unit as it was over 10 years ago I used that one. Different brands of paint will also require different ratio and some you may have to add flow improver and retardant. If you make it too thin normally is not an issue other than you may have to put an additional coat on. Sometimes I've tried to do that for a base color to bleed through. Also when you get a dual action brush and you want to do finer detail you will want it thinner than normal and the air pressure turned lower so that you can do a finer line or get into a tighter space with little to know over spray. If it is too think it will kinda spit out the end or not come out at all. If that happens just add a little thin and take the tube of and add a drip in that and where it plugs into and you should be good to go.

It can be intimidating when getting started. But just keep in mind it is not that difficult and it is mostly trial and error and there is almost always an easy way to resolve having the wrong ration. The skim or whole milk consistency is the easiest visual way as a good starting point.