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! 

Appreciate them the way they are, ensure what you are doing is not pushing them more away. 

Do things together...cook, go for a drive, lots of things that could present discussions.