With a young person you are more likely to say things that are positive behavior reinforcement, but might sound patronizing to someone your own age.

If you see a young guy really striking out when he talks to girls you might laugh and then pat him on the back and say in a sarcastic tone "let me give you some sage advice from a true lady killer" and then give him your tips. This would be super patronizing for a 30 year old guy to hear, and you would have to go about it a different way.

A recent example, I was doing lawn work at my friends house, it was me, my friend and his nephew. His Nephew is 15. We had a wheelbarrow filled with 120+ lbs of dirt which needed to be moved up a rather steep hill. The young man has seen us muscle it up the hill a few times before it was his turn. Eventually we ask him and he tries too muscle it up the hill, but he uses too much force and it tips over to the side. Boys at that age don't really know how to use the new found strength that they have which is why older men can seem so much stronger even when they are the same size. "Old man strength". So I picked up the wheelbarrow and gently rocked it back and forth to sense the weight properly before gently but forcefully moving it up the hill, and as I started to move up the hill I said something to my friend's nephew "All of those muscles and no finesse, you have got to learn to be smooth with it, the ladies love it, strong but smooth. What you just did will get you kicked out of bed in a hurry".

Whereas if it was someone my own age I might just say, try taking it slow, get a feel for the weight and then start moving it.

Generally a sort of avuncular tone is a good way of putting it I think. I get a feeling from recently transitioned transmen based on their behavior and sense that they are youngmen and treat them that why.