I guess my question was, what you do when someone is indeed ready to hear you.
It depends upon what information is desired. If I know the truth, I explain it without apology. If I am asked a question on some obscure issue, I explain that I do not know. Actually, the Conciliar church that most people think is the Catholic Church gets in the way much more often than true doctrine.
It is unfortunate, but it is very difficult to explain the Catholic Faith to someone who has met a Conciliar priest who has told them something very different; for example, that aborted babies go to heaven or that salvation is based on how "good" or "nice" a person is and it really doesn't matter what church one belongs to.
By the way, I find indifferentism is much more prevelant amongst the Novus Ordo faithful than among the Protestants.
I've had only one opportunity to discuss the faith with a Muslim. The opportunity came when she explained that Islam considers Jesus to have been a great profit. I replied that if that is true, Islam has proven itself wrong. I explained that Jesus is either God or he is a liar and a fool. I then showed her the numerous instances in the Gospels in which Jesus specifically and unambiguously says that he is God and not merely a profit. (I am frankly amazed at the number of times Jesus clearly claims to be Divine.) I explained that a person who specifically claims to be God clearly cannot be His profit. Did she convert? Well, unfortunately, no. She did after a time abandon Islam but she returned to her childhood Southern Baptist religion. I could no longer discuss Christianity with her as our conversations were held over a period of some weeks while we were in the U.S. Army stationed in Korea our transfers prevented me from getting her steered to the Catholic Church.