Info needed: How to search for birth mother in NYC

Hello! I'm looking for concrete information about how adoptees can search for birth mothers in NYC. I've gotten so much misinformation online and in books. I'm not even sure where to begin. I know I was born in New York City in the early 1980's. It's my understanding that adoptions were all closed then, but the laws seem to change frequently so I can't be sure. It is hard to follow what step makes the most logical sense to pursue next. Try to get my real birth certificate? Try to contact the agency where I was adopted? I've heard they can't give out much information.Has anyone had experience searching in NYC and can offer guidance?Has anyone ever used an adoption detective?Thanks!