Hun, you can just start one thread and ask all your questions there instead of starting a new one for every question.
Make sure to clean your brushes between clients, if you're using the MAC brush cleanser, it should take 15 minutes for them to dry, so anticipate a 20 minute break between clients so you can do this.
Also, sanitize every product before and after you use it. Make sure you're educated on all sanitization procedures, because you don't want to risk infecting your kit by getting bacteria on a product.
Another thing that helps is to carry three or so of each type of brush you need, that way you don't always have to clean between clients.
I have three full sets, I could get away with doing three faces before I had to start cleaning at least one or two brushes to get by.