Make sure you give students adequate time to formulate a response to your questions. Just by adding more "wait time" to a question, you often get better results.
Respond by acknowledging students' comments with a few words ("That's an interesting point"), probing a little deeper ("Do you think that's true for all circumstances?"), paraphrasing a long-winded or confusing answer ("So what you're saying is..."), or asking other students to respond to the answer ("John, do you agree with Lauren?").
Look at your students and wait until they are finished talking before responding. Make a conscious effort to try and wait a while longer during question-and-answer sessions.
Read these comments from Jeanne Carlson about responding to students in a way that encourages learning.
"...When a student asks a question, the tendency is to answer them. What we need to do is answer their question with a question. Well, you've done this, so what do you think? What do you think you need to measure? What would you have to do to come up with an answer? So I try not to just answer directly ever. We just try to guide them on the pathway that will allow them to figure out., because if they can figure it out, they're going to remember it a lot longer than if they just get a direct answer from us."
— Jeanne Carlson, Mathematics Instructor, Sinclair Community College