You get a star everytime you reach level x5 or x0. Like going from 74 to 75 or 79 to 80.

You can't place a player on the negotiation list, but he will be placed there, when he only needs 1 skill point to get the next star.

So be careful when he reach x4 or x9, and the percentage is on 99%.

Also, when he gets near the next star, don't train him with hard programmes- Only them on very low or low.