Bridal party hair and makeup

Rule of thumb for hair and make-up is if you are requiring them to get professional services, you should pay. If it's truly optional, they can pay. It's not fair to require a service that you want them to have if they can't afford it/don't get a say in on top of other expenses.

If optional, present it as "for those interested in hair and make-up services, prices is $X amount. Please let me know if you would like me to put you down." I would also request payment a few weeks before the final amount is due.

If you are requiring them to have their hair and makeup professionally done, then you should cover the cost. If you're giving them the option on whether or not they want to have it done professionally, or do their own hair/makeup, then they can cover their own costs. If you're not requiring professional hair and makeup, then another option could be for you to cover part of the cost to help make it cheaper for them, and they cover the rest.

I covered the cost as a gift. I didn't require it though- simply asked ahead of time who might want to have it done and then surprised them the day of with paying for it myself.

As PP stated, if you are requiring them to have their hair and makeup done, you should be the one that pays for those services. If they are being given the option to either do their own OR have professional services, then you can extend the offer for them to utilize your h/mua and let them know the cost to do so. Personally, I think it is always a good gesture to pay for hair & makeup for your WP. I gave all my girls the option of having services or doing their own, but paid for everyone regardless.

If it's important to you that your bridesmaids have their hair and makeup done professionally, then you'd need to cover the costs. If you don't care how they look and professional hair and makeup are completely optional, then bridesmaids could cover their own costs/chip in. I went with option 1 (paid for everyone) because that is the norm in my social circle. I've been a bridesmaid 8 times and never had to spend a dime on hair and makeup. If I were a bridesmaid and professional hair/makeup were presented to me as an option that I would have to chip in for myself, then I'd most definitely decline and the bride would just have to deal with my hair looking frizzy and/or makeup possibly not up to her standards.

Etiquette wise you have no proper authority over how your bridal party wear their hair. You can generously offer to pay but that still doesn’t obligate them to use your stylist or anyone if they prefer to DIY. Alternatively you can offer the access to hair and makeup services where they would be responsible to pay but again, that is optional.

To be really prepared before asking someone to be a bridesmaid, it is better to know what your hopes are for them as far as makeup, hairstyles, travel, money commitments, and assistance. More than any of these things, you should let them know they don't have to obligate themselves to any of these -- that ultimately it is having them at your side.

When we were dress shopping and talking about the big day, I just told them that I’ll arrange for a hair stylist and pay for it, but we’ll all do our own makeup.