Use the following trick to get your player up to 99 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 and you will see your players 
overall climb until it reaches 99. 

13. Once your player has an 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 there in case you want to do this again.