Matt,
do you know what type of adoption you are looking for? Open, semi-open or closed? Domestic I assume? What about the child - you said it doesn't have to be a newborn - does that mean you intend or would like to go through the state/foster care system? or would you prefer an agency that deals with newborns/babies and the occasional toddler? Generally agencies have preferences on what types of adoptions they do - some only do closed adoptions, some only do open, and some to all...so, that is the first step. If you need help deciding on what level of openness you want, just ask - I can give an earful on why you want an open adoption!
If you didn't understand a word I just said, let me know that too - love to help, but love a little more info...then maybe I can help point you in a direction!
Congrats on beginning the process!