Agency Choice

Hi, I would like to ask for some help in choosing an adoption agency. I am 40 years old and I am a single female. I was born and grew up in Poland and now I live in the US. I would like to adopt a child, preferably a girl, 3 to 6 years old, from Poland. I have started looking at some agencies but it is really daunting to choose and commit to one... Would anybody be able to advice and recommend an agency? I would very much appreciate some information.... Thank you