The real challenge here is coming up with something genuinely positive that a person might not know about themselves. So that rules out things like commenting on someone’s looks and things of the sort. 
I mean things like managerial skills or being able to stay at an even temperament under stress. 
I have to work with some gang members. Guys that revel in violence and promote preying on the weak. I got to talking to one of them one day and discovered that he doesn’t like bullies. Strange that a man here for murder and nearly proud of it, doesn’t like bullies. So this caught my attention and I began to see another side of him. Then I noticed something odd, I realized that no matter what was going on, no matter how much stress was going on he stayed happy and calm and was always able to set everyone around him at ease. Everywhere he goes he makes people feel confident and happy he’s here. These are great qualities for a Project Manager and if he applied himself he could really be a great asset to a large company who needs things to get done on time and properly. 
So I told him so. Then I let it ride. He seemed uninterested. Then about one month later he pulls me aside privately and starts asking questions about where to get schooling and if he can do it from prison and if his criminal history would be a problem. 
Do you know what blows me away most about him? No one has ever told him he’d be good at anything but gang banging…ever. I was the first. 
Here is this man with an amazing skill set and he never thought it could be used outside of gang life. But in reality he’s Fortune 100 material and he’s been thrown away by everyone he knows. Well, he won’t be thrown away by me.
So my challenge is simple, everyone you know has something about them that can be nurtured into success for them. What if no one they new told them and what if by you telling them they have a wonderful quality they don’t commit a crime? What if…You just might change someone’s life. 
Once you’ve told them, be prepared to lead them to a place that can help them develop that. A college, a mentor something useful. Don’t lead them into darkness and then leave them. Help them do some legwork. Its a small price to pay to take an hour and help change a life.

With Love
Jeff Utnage