I will say, take my tips AFTER you get good with gradients and blending.

Another thing that could help, in terms of cost; don't use a base coat with the air gun. It takes too damn long to paint, and to dry for that matter. If you do a base coat with the air gun, it can also warp the paper because it will dry at different rates. Also, its a hell of a ton cheaper than going through a dozen bottles of air brush paint when two sprits of a spray can could do the same.

Use spray paint for base coats. Prep canvases ahead of time with spray paint and let them dry flat in a well-circulated area. This will also help prime the canvas and prevent the air brush from warping small spots because it seals the canvas away from the solvents.

Ones last material thing you can focus on as well, depending on your chosen canvas, are paint thinners.

https://www.youtube.com/watch?v=-EWWFd8ij-g

What he sprays down before literally carving out the buildings is paint thinner. It allows him to move the paint on the canvas. The canvas, spray paint, AND airbrush paint all have to be able to handle whatever paint thinner you choose, so experiment well and make sure you test what happens when the piece finally dries, so it doesn't peel away over time or in the sun.

The only last thing I can say, is that you can also dip brushes in the paint thinner and flick the tips of the brush over a stick (so the brush fibers hit the stick and the dropplets are catapulted at the canvas) to create speckles like stars. The droplets form on the canvas, and nice clean round speckles can be made this way which will have a tinge of the paint around them in it instead of being dead white. Again, it depends on your materials, but it sure beats the hell out of using stencils or individually painting little stars.

Glad I could help.

Remember, half the fun is finding something new.

90% of the time, the thing you plan on and spend all your energy to make, which you think is your best work yet, typically doesn't strike anyone else as impressive.

The best works, you'll find, come not from planning but from originality.

That is to say, you'll stumble upon your best work and in spite of how little effort you thought you put into it, it's what everyone seems to resonate with.

Remember what I said before about when it becomes easy for you?

Even though you think you put in little effort and cannot fathom why others like THAT piece as compared to all other ones you may have slaved over, recognize that the only reason you think it was low-effort was because you only used all the skills you've compartmentalized (therefore mastered) and don't even realize you're doing it anymore.

That's why people usually like the ones you think are throw-away and run-of-the-mill better than the art you slaved over, made all the grand plans for, and put everything into. It's funny how it works out that way.

They are responding to your journey, not your destination.

Remember, half the fun is finding something new. Ignore WHAT you're creating and instead focus on HOW you're creating. Loving the process not the outcome is the only way you'll never get bored or feel like you've run out of ideas.

Once you accept that, you'll find you've made more pieces than you can count and you'll be baffled as to where they came from all of a sudden.

You drew me!