Tipping and Prep for Hair and Makeup Trial?

Yes, you need to tip at both your trial and on the day of. 20% is a good amount.

I'd ask your stylist what she prefers. Most updos actually hold better if the hair is not freshly washed (about 1-2 days old) since it will grip better. I'd suggest no makeup but, you can ask about that too. Yes, bring your veil and your inspiration photos.

20% is standard, I think, for most wedding vendor tips (except your caterer which is usually based on headcount). I'm going to tip mine somewhere around there (for myself & 4-5 other people). Total will be around $600-700 so I'll tip between $120-150 depending on how the day goes & the fact she's bringing a second person. That price also include my trial, which is included in the package.

How your trial goes varies by hairdress/mua so it's best to ask them their preferences. Some want clean hair, while some want unwashed. Some want you to come in your base, some want a clean face.