making stars

You could use a clothes peg, check out the tutorials page on if im not mistaken Mitch has a TUT on it
You can also reduce the airpressure till the point the paint doesn't atomise anymore and you get little specks, this gives the same result (also the method I use)
I use a wood stick from an ice cream bar. That will get you a good stiple effect. Or just dont reduce the paint and itll come out splatterly (im pretty sure thats a word) like it does on a piece you dont want it to.
Depending on what look I am going for I either use the low air pressure like haajse or ice cream sticks , I have also tried the panty hose trick where you stretch the hose over the end of the airbrush and spray but that is better for stone more then starts
The cost efficient option is to use the sticks. I personally use a spatter cap on my H&S Colani. The same cap is compatible with the Evolution and Infinity lines. I've found it works best with the .4mm nozzle/needle set. I have much better control on the spatter size and location using it.
The tongue depressor or ice cream stick trick is the best. Or if you use a gravity feed gun, you can flood the nozzle with paint and then just give spurts of air.