Hi,try to thin 50%,anyway the old rule of milk density is often right.You can olso try to spray around 15-18 Psi to avoid the over spray,all dipend from your hand and from what kind of work you are doing.....Ciao Enrico.
P.s. If you are working free hand (without masks) and you need soft edge the low work pressure help you to achive a good camo with minimum overspray,but i don't know if your airbrush can work well at low pressure.In case try to thin your color up 60-70 %.