My son has been in speech therapy for the last few months. He sees his therapist once each week. She does some good things with him, but he needs to be involved every day in developing his speech so I've been reading books hoping to learn some techniques to help him.
Since I live in the boonies, I frequently turn to Amazon for my book needs. I looked at several different books including It Takes Two to Talk by Jan Pepper and Elaine Weitzman. When I asked the therapist to recommend a book, she actually gave me this one to read.
It has some good advice. The authors suggest you OWL with your child. Observe. Wait. Listen. Instead of forcing a conversation, observe what you child is interested in. Ask him about it and wait for his response and then listen to that response.
This book suggests first teaching your child to take turns so he understands that conversations are about taking turns. If you let your child take the lead (sometimes hard to do) and are tuned-in to what he wants and/or is interested in then it's easier to have a conversation with him.
The book also has some checklists to see what communication stage your child is at: Discoverer, Communicator, First Word User, Combiner. My son is between the stages First Word User and Combiner. The authors emphasize that a First Word User doesn't necessarily use words but may use signs and a Combiner is one who uses more than one sign to communicate something. Today, my son used signs to ask for an ice cream. He combined the signs for "please" and "ice cream." He also uses the sign for "want" with other signs. He uses the sign for "all done" frequently. He has a signing vocabulary of about 30 words and is learning new ones every day.
I learned some things from this book. It retails for over $50 and I'm not sure I'd pay that. If you can get it at the library or borrow it from a therapist, it's worth reading.