When you are building your birth support team, it is important to choose people who share your common beliefs (your doctor or midwife included), and who you feel comfortable with. If you decide to hire a doula, there are some important things to take into consideration:
First off, what does she charge? Does your budget fit what she is charging? Does she provide insurance receipts? Doulas work in all different price ranges and it's not impossible to find a doula to fit your budget, even if it's very small.
How does your doula support you during childbirth? Every doula is different and practices differently. Some doulas are really hands off, while others are really hands on (and many doulas are in between too). My personal philosophy as a doula is to provide whatever support the woman needs in the moment. I've gone to births where I thought they would need more support, but when I got there I realized they really were doing quite well without me, and that I actually slowed labor a little (which is quite normal with a change of environment). If I was a doula who thought every woman needed to be saved from her pain, then I may have tried to be near her and rub her back, when actually she needed me to hide away (which I actually did!). Ask your potential doula what her philosophy of childbirth is and see if it fits yours.
How reliable is she and how many births does she take on per month? How many times has she had to call her backup doula? This is something to take into consideration - doulas who take on more births are more likely to use their backup doula. If you're okay with that, then make a point to meet the backup doula before your estimated due date.
Do you feel comfortable with her? THIS IS PROBABLY THE MOST IMPORTANT!!! If you don't feel comfortable with her from the start, then you probably won't feel comfortable with her on your baby's birth day. This can actually stall or slow labor. Even if she's a super experienced doula, if you don't feel comfortable with her, then pick somebody else that you do feel comfortable with.
Most doulas offer a free get-to-know introductory meeting. This is a great time to ask the above questions (and any others you want to ask). I hope this article helps you find the best doula for you.