How do you keep your teenagers self esteem up?

[SoTiredNeedHoliday]

Just wondering if there are any hints out there that might help me keep my teenagers self esteem from falling.
He has huge potential but is desperately afraid of failing, so in his teenage mind it is better not to really try as he might get something wrong.
I've tried all kinds of praise and support etc but he just doesn't seem to want to believe he is capable.

I know its not uncommon at all, but I wonder is there something else I could be doing?

Have had the same with my son. Had a talk with his head of year and yes it was the fear of failure. Now with a couple of months left I sometimes sit with him and talk through what he's doing. Or plan the next steps with him. I'm trying to let him get on with it but at the same time trying to make him feel he's making the revision decisions. I feel like he should be putting in more hours/effort but he keeps telling me he has it in hand....Crossing fingers but persistent , supporting . It's so hard.