There are many footballers who could have been fantastic players, but their work rate really let them down. Work rate will decide how well a player will progress in training and how much effort they will put in on the pitch also. I tend to always look for this as a key attribute, no matter the position of a player (central defenders might be the only exception).
A player who is professional will train a lot harder and as a result will develop quicker as a player. If you have a temperamental player, eventually he will most likely fall out with you and potentially other team mates. A players personality will effect how he reacts towards you and towards training. If players are over the age of 23 and they have a high enough squad status then they will be able to tutor younger members of your team. I believe personality is a huge factor in developing wonderkids, make sure you have players in your squad who have professional or spirited personalities. If a player has a decision attribute of say 5 or below, then generally I will release him. As a general rule of thumb, I like to make sure most of the young players who come into my youth teams have a decision attribute of at least 8-10. If you offer your player the correct training also he can develop his decision attribute further.
If you have a player who is a full international and is playing in the Premier League, he will develop alot quicker than a player who is playing in League 2. Depending on what level you are managing at will decide how quickly this attribute will increase. The best way to improve the decision making attribute is through game time.
It could be said its what makes a player turn into a world class footballer. Being able to make the right pass or to decide when to make a run or try to tackle an opponent would all be decided by the decision attribute. The decision making attribute on football manager could be classed as one of the most important attributes. It is worth noting that not all players with the below will turn into wonderkids, a bit of luck along the way always helps, but for me, when I am searching for wonderkids on FM 2017, if a players does not have the below then I really do have to think twice before signing them.
There are several key attributes to look out for when trying to look for wonderkids or key signs that your scouts will tell you about, when they produce a scout report. These wonderkids, ideally would have generated from your own youth academy, in some cases you will need to, with the help of your scouts, search for wonderkids. When playing Football Manager 2017, it is every managers dream to have a team full of wonderkids.