Bow to me you peasant!
I'm kidding. Look, having 300-400 tokens is useful. But is more than you need. If you want to be successful try buying 3 or 4 high value and wage under 21 year olds. Don't forget to look at their previous form. You might find a hidden gem. If he has form like 8-9-8-6-8 chances are he'll have similar form for you. Some players play better than others.
What I do is I find some young fast trainers, I make sure they perform and when I can I use green packs to train them. 180 greens will add a star and a special ability. These are the kind of players that last seasons and seasons.