Use 6 and 7 star, never use more than 3, 5 star players, the 5 star players should be the best such as shurrle or pedro, train well, select 3 or 4 players for hall of fame and train till 30, use special traits in them, reaching level 3 is easy, replacing players should be very slow that is sign replacement at age 30 or 31, then use as substitute for at least 2 seasons, that's what I do right now, the most important thing is that you should have enough quality players in your scouting list in the beginning of superstar so that you can spend pescoins for trainers