Plan with them and watch a movie. Certain aspects of the movie will promp questions, answers and discussions
Kids know when you are genuinely reaching out to them.
Give them scenarios, ask what they feel or what they would do in those scenarios
Be patient with them
Have the ability to recognize their body changes (teenagers) mood, likes, dislikes etc
Teenagers could be confused about body changes. Explain over and again so you are sure they are not living in fear.
They are normally deep thinkers!