The Paint is Splattering:
There are a couple of ways to unblock it. Firstly check if tiny hole in fluid container cap is unblocked. Try cleaning the air cap this usually gets a build up of paint quite often especially when using temporary tattoo paints. After unscrewing the aircap with a clean cloth gently clean the tip of the needle, you can usually see paint build up here also.
After carrying out these two steps test to see if the problem has been rectified. If still splattering apply high air pressure facing onto a rag ( by pushing down on the trigger and all the way back at the same time) If the problem persists check paint viscosity. The paint you are using may need thinning, if using Airbrush body paint thin with a little Isopropyl Alcohol.
If you are still having problems you may need to do a complete pull down and proper clean of the airbrush. (Never completely emerge your aibrush in solvent based cleaners as you will damage the tiny seals inside the airbrush.)