Also PLEASE don't let them file your natural nail. Some of them will do this on purpose as it weakens your nails so you keep wanting acrylics on, hence keeping them in business
this is what happened to me. i had a set put on and she filed the actual nail. not the tip, but the whole of the nail. she was at it for ages. then when she put the 'nail' on it was agony. the stuff she used made my nails sting and it hurt for ages. she told me it was because it was the first time that i'd had false nails on and that next time it would be alright.
the time i went back to have them filled she filed them down even further and they bled.
that night i went to a friend and she took them off for me and ive never had them done again.