Bring money.
LOL, jk. But most MAs like a bare, clean face, so go there without makeup. It will save time and sometimes getting everything off (eye makeup, etc.) with a wipe at the store gets messy and it leaves a residue. They will usually ask you what kind of look you want, so try to be specific. If you wan the MA to "play" then tell them that too.
I normally tip $5, but I honestly don't know if there is a rule or expectation like there is with waitresses. I think whatever you can give is nice.