Steering a conversation is a useful tool which can be used to bring up a topic that is currently not being discussed. The key to steering a conversation is to not let the other person or people know they are being steered.
First, you must gain control of the conversation. You must make it so that everything the other person says is in response to what you are saying. It helps if you can get the other person emotionally involved to some degree, by incorporating issues such as abortion or the environment into your discussion.
Once you have control of the conversation, you can steer it, but be careful. You must work very slowly, changing the topic to something slightly different every two or three statements.
When you have reached your destination, deliver your payload. Payloads can consist of persuasive arguments, which I think is the most purposeful, or anything else you choose, but keep in mind that you still want to keep the other person uninformed of your act of steering the conversation.