Do I tip my hair / makeup artist after the trial?

I did, just for good measure, but some people don't because they say the will tip them day-of.

I did. I also ended up having two complimentary trials after my first because both my original hair stylist and MUA weren't able to do it. Even though the trials were free, I still tipped.

ETA: I just noticed you asked how much if they're free. Trials at my salon cost $50 each, so I gave 20% even for the free ones.

I was planning to. I figure I always tip when I get my hair done, why would this be different? My trial isn't free though so it makes it a little easier to give a tip.

I did, my trial wasn't completely free but was deeply discounted. She did a great job, plus the poor girl got to field questions from my FMIL about just what shade of red her hair was.

Yes!

Maybe not free but bundled into the cost... Thanks all!! Appreciate it. Off to my trial this morning.

I'd tip, same as getting your hair done any other time!

I tipped 20% (actually a little more)of the trial cost and I will tip 20% for what it costs for the day of. Also my trial was not free.

This is a great forum! I didn't even think about it honestly! I will definitely tip, just because I love my stylist!

This is a great question! I was going to tip but wasn't sure how much.