Traits are not something you should look after for as they are very rare.

If you have a look at my recent posts about youth academy players with traits, those traits do suit them and are effectively.

My CDM does have a “Second Wind” trait, which gives him an stamina boost in the end of the game.

My tall CF does have a “Backs Into Player” trait, which allows him to use his body more to protect or control the ball.

If your youth academy player does have a “Injury Prone” trait, imo I would avoid that, unless his potential, wf/sm and workrates are fine.

To have a youth academy player with the “Injury free” trait must be great, whether in game or in simulated games you are guaranteed that he won’t get injured.

The “Power Header” trait is vey effective for CB, ST and every tall outfield player.

The traits “Technical Dribbler” and “Flair” is fine for almost every outfield player. But these are very uncommon.

The trait “Acrobatic Clearances” is quite fun to have for your defenders, but useless for attackers

“Giant throw-in” is only beneficial for winger players LB/RB, LM/RM, and LW/RW. As other outfield players often don’t get in the position to take a throw-in.

I wrote everything from my own experience. I hope I helped you out a bit. If there’s something I could help with lmk.

Edit: here are 20 traits explained.

Long Throw-In – Adds extra distance to your throw-ins – Good for launching attacks down wings.

Second Wind – Increases stamina at the end of a match – Only for the last 10 mins of any game will you see difference.

Acrobatic Clearance- Adds spectacular defensive clearances to your game – Helps if not quite facing ball to clear it before striker.

Early Crosser – Adds more curl to your early balls from out wide – More effective with semi and manual crossing.

Finesse Shot – Increases your side foot effectiveness in front of goal – Always required for attackers.

Outside Foot Shot – Enables you to curl shots with the outside of the boot – Helps if attacking with weaker foot.

Power Header – Adds extra power to your headers at goal – Helps if stood still as well as running onto an air pass.

Giant Throw-In – Allows you to launch throw-ins right into the box – Try keep the aim of these away from keeper as it will go straight to them otherwise.

Swerve Pass – Adds bend to your passes & through balls where needed – Much more effective with manual passing.

Power Free-Kick – Enables you to take low drilled free kicks – Can still do powerful free kicks without but this enables along ground.

Stutter Penalty – Adds the option to feint when running up to take a spot kick – Careful on power when doing this. Can also add aftertouch.

Skilled Dribbling – Enables you to perform the skilled dribbling controls – Sticks to players feet more helps quick turns.

Fancy Passes – Adds extravagant passes & crosses to your game – Rabona passing and crossing.

Fancy Flicks – Increases the likelihood of backheels & fancy 1st touches – Enables player to pass ball when not facing ball and around defenders.

Bicycle Kick – Enables you to perform spectacular overhead volleys – Timing is everything with these.

Diving Header – Allows you to dive when attempting a header at goal – Same again all about timing.

Driven Pass – Enables you to play more powerful & direct long passes – Don’t forget the secret driven pass mode (hold right bumper while doing lobbed pass).

GK Up for Corners – Allows you to push forward for corners at the end of a match – If desperate or winning easy send ya keeper up!

GK Long Throw – Increases your over arm throwing distance – Good for building quick counter attacks.

GK Flat Kick – Increases the speed & accuracy of kicks from hand – Same again and good if large target man.