1. Look at their previous work
Can you envision yourself in their style of hair and makeup? If you want a sleek, low bun why would you hire someone who specializes in boho styles? If you want natural makeup, why hire someone who specializes in goth makeup? Hiring someone whose work reflects the opposite of what you are looking for is not going to get you what you want.
Don’t hire someone because of their potential, hire them because you know they can help you achieve your desired look. Afterall, you wouldn’t…or shouldn’t hire an exclusively landscape photographer to capture your wedding.
Plan your beauty prep around the way you want to structure your time. For example: you are planning to get ready the morning of your wedding with all your bridesmaids at the cutest bed and breakfast that is an hour outside of town. There's no way you'll be able to drive back into town to go to the salon and to another makeup studio and somehow not be stressed by the time you get back to the BnB. In situations like this it's much more convenient to hire a beauty company that offers both hair and makeup but is also mobile. That company would come to the BnB allowing enough time to pamper the bride and bridal party so they can enjoy the day.
Make sure to choose an artist who offers services that align with your wedding's aesthetic and what you envision as your bridal party's 'look'.
3. Look at their reviews
If you look at their reviews, you are likely to see common themes in what people are writing. Chances if you see that they are “punctual and friendly” repeatedly, they probably are!
4. Are you able to communicate well with them?
Everyone communicates differently whether it’s in person, over email or on the phone. Are you getting the necessary details from them and in a timely manner? Are they answering your questions? Can they help you prepare?
5. Availability Lastly, availability is key. This one doesn't need any explanation. :P