Tipping

how much are you suppose to tip your make up artist and hair stylist for the day of wedding?

my hair stylist is charging me along w/ my bridal party a total of $600. and for her trial, it'll be an additional $85 -- do i tip both too?

my make up artist is charging for all of us a total of $900, and an additional of $150 for the trial...

please help, thanks!