Here is a great exercise - a favorite of mine I practice this in all my lettering that I do with handwriting : start with the first one and a roll of paper towels is inexpensive so try to feel a thin line and once you know where thin is try to thick and back to thin .. you should feel your finger moving back and fourth while your hand is in a spiral .. draw the spiral with hand and wrist work the line thickness with the trigger .. same speed same distance .. paint can’t be to thick or line will wiggle or airbrush will have delay in spray .. Hope you have fun and enjoy .. it’s better to learn and grow than to be perfect . Have Fun!