If the stadium is now maxed out for VIP and executive seats, then you can look at the coaching staff. It's best to have enough money to max out the staff you want to level 20, rather than doing it in stages as it's more expensive that way. Training hall is another option which will improve the speed of training physicals. Personally I did the training hall first, but I'm sure others went coaching staff first.

I would only suggest that when you go to buy your level 20 coaches, think about only buying a kicking coach of level 5-10. Mine is only level 5 and I think it's a waste of money to carry a level 20 kicking coach. All the other coaches can help the training of your entire roster. Once your kickers are trained up to the level you want, the coaches there are kinda worthless until you go to start training a youth replacement. There is plenty of time to train up youth kickers slowly

Thanks for you're answers

You could also go for the 'Club Shop' - Can't remember the numbers, but the return of investment is pretty good on it.