S.P.
Hi, I used both an attorney and an agency.(You will always need an attorney for any adoption, and all agencies have attorneys that they work with, although you're welcome to use your own.) My situation was unique, in that the adoption attorney was a family friend, and once she knew I was open to any race child, she offered to notify me if an expectant mom came her way that none of her clients were interested in, at no cost.
So I signed with Family Resource Center here in Chicago, but also had the private adoption attorney "looking" for me. In the end, she found my daughter before the agency did, but I still had the agency do my home study.
By law, you must complete parenting courses and do a home study, and these are done by adoption agencies. But you can still use an adoption attorney to find your baby. You will pay for ads in newspapers, and it can get costly. The advantage to using an agency over an attorney is that you pay one fee, and if the birthmother changes her mind, you get put "back in line" for another baby. With an attorney, you often pay birthmother expenses, which are non-refundable if the birthmother changes her mind. So the agency financials are fixed.
I hope this makes sense. If you are open to transracial adoption, and open to gender, your adoption will take much less time. I got my daughter 10 days after speaking to my attorney!! (I do think this was a fluke.) My daughter is African-American, and the light of my life. If you have any questions about trans-racial adoption, or would like the name of my attorney I'd be happy to share lots of info.
Good luck! Your child is out there!
S.