The biggest tip I can think of is to play around with your gun and get the paint mixtures, and pressure so that the paint flows freely and you feel comfortable. That takes some experimenting as all paints are different, but when you've nailed it you'll know that when you're practising different strokes, any issues will be with perfecting technique not gun problems. And having a gun that is working well will make the learning process way less frustrating, and quicker and easier too.
Then it's just practise, practise, and yet more practise.
I agree with Squishy learn your airbrush , and pick one brand of paint to start out with. Why , I found when I was jumping from paint to paint I was getting more upset and ready to chuck the whole thing. After picking one and learning how it sprayed ,reduced , and at what air pressure it worked best at I picked it up faster .
Other than that Dots Dagger strokes , fades and blends.
No matter what you paint it will have all those in it.
Use home made stencils , store bought one what ever tool it takes to get the job done.
and the main thing is not to stress and have fun while you are painting.
Don't bother with seeing how fine you can get the lines or try any skulls or flames. We all try that in the beginning and until you have done many sheets filled with dagger strokes, blends and dots, you will not succeed.
My tips would be:
Have fun when you practice.
Use colors that appeal to you.
Keep your early practice sheets and put the on date them. When you hit the wall and you feel you're at the same spot, you can look back at where you started. You will be amazed at your progress.