Set your Youth Team level to 5. The next year in Master League you will have at least two stars in your youth team. For example, as Barcelona the youth team spotted Klasnic 16 and Amanatidis 18. Other teams also have stars. Go to advanced search. Put in 15 to 19 for the age. For example, Carson in Sampdoria, H.Larsson in Racing Club. Teach them lots of Ability Cards and Positions to make them better than they are and also loan them out.