Sometimes children talk a lot - about lego or princesses - or whatever their latest fixation is. By the time they're teenagers, all they do is grunt when you ask where they're going, who with - and what they're planning to do.
There's a cute saying:
Listen to the little stuff when they're little, and they'll tell you the big stuff when they're big. Because to them it was always big.
Tips for good listening:
DO ask clean, open questions. 'What happened next?' 'What did you think about that?' 'What's that?'
DO talk about feelings: 'I bet that made you annoyed/upset' or 'Did you feel pleased?' 'How did you feel about that?'
DON'T offer opinions, advice, tell them what to do or pass judgement. Help them work out a solution to a problem by asking: 'what do you think you could do about that?'
DON'T use emotive language ('disgusting', 'dirty', etc).
Bedtime is a good time to talk to them, when they're feeling relaxed. Build a five or ten minute chat into the night time routine when they're little. When they're older, you can chat together in the car, or some other time when there's more privacy. If there's a regular time they chat with you - once or twice a week - it's easier for them to casually ask about a problem. It's harder if they have to seek you out and try to get you on your own.
Ask questions like 'do you have any worries?' - for young children and teens - or 'did anything happen today?' Show that you're interested in what they have to say by repeating back small chunks of what they've told you. Ask questions about what they said.
Don't rush to fill a long silence after you've asked a question. Let it hang. Then maybe they'll tell you something they're finding hard to say.
For more information about getting your child or teenager to open up to you, you might like to read Clean Language.
And yes, a lot of this works for adults too! Being a good listener - and paying attention to other people - are key points in Dale Carnegie's famous book, How to Win Friends and Influence People.