Use the following trick to get your player up to 99 overall a lot faster. Before 
you start, make sure that the player you want to upgrade is your arena player.

1. Save enough points to buy all the experience packs in the shop. 
   This should not take too long.
2. Once you have enough, save it onto a second personal settings as well as 
   your first.
3. Buy all the experience packs in the shop, and save as normal. 
   It should save to personal settings 2 and your squads.
4. Use all the experience points on your chosen player.
5. Save the game as normal.
6. Load personal settings 1.
7. Save it to personal settings 2 again.
8. The experience packs should now be available in the shop again, and you 
   should have your points back.
9. Buy them again and save as normal. It should save to personal settings 2 
   and squads as before.
10. Use all the packs on your player again.
11. Save as normal.
12. Repeat steps 6 through 11 to keep increasing your player's stats until he 
    reaches 99 overall.
13. Once your player is 99 overall, save and load personal settings 1.
14. Save it to personal settings 2.
15. Load personal settings 1 again.

Your chosen player will have 99 overall, you will still have all the points you 
had before to spend on whatever desired, and have personal settings 2 to use in 
case you want to do this again.