How do you choose your hair and makeup artist?!?

There are so many different companies and people out there and I'm just finding it so difficult to choose. I dont know how much i should be spending and im no makeup expert so i dont know what I'm looking for. I dont know how to decide, what questions should i be asking? what should i be looking for? Also whats the difference between airbrush and traditional? Will airbrush be better if my wedding is in summer? Hellllpppppppp pleaseeeee