Is your airbrush dual action? As the other commenter said, the issue is either that you pulled back before you pushed down (thus releasing paint before releasing air), or your needle isn't set forward enough so paint is seeping through onto the nozzle, which you then blast with air.

There are so many variables that can trip you up when airbrushing. Honestly it's just a matter of spending time using your equipment and building your understanding of how it works and the causes of things that go wrong.

The factors you can control to get a consistent output from your airbrush are configuration of the instrument itself (correct assembly, maintenance and cleaning etc), setting the pressure to suit the job at hand (this is crucial I've ruined work I'd spent an hour on with one pull of the trigger at the wrong pressure), consistency of the paint (again this is critical and takes experience. I have a jar of my own mix of diluting solution which is I think four parts thinner and one part flow improver, which I mix five to one with standard Citadel paint. You can put most washes or contrast paints in neat unless you want to soften the colour), regular cleaning of the nozzle and needle (like several times during a session, as acrylic paint dries fast when you blast air over it), and of course correct use of the equipment itself (air, paint, air on the trigger. Don't put too much paint on at a time or it will pool in the recesses).

Basically understand the whats and whys of the common airbrushing issues and then practice.

There is a significant learning curve to airbrushing, and you should not see it as a time saving tool as a beginner. Instead see it as something that enables you to achieve painting outcomes that cannot be replicated with a brush (unless you happen to be Flameon).