I put a post earlier about getting rid of transfer fees, bringing in a short contract and trade only system a bit like the NFL.
Get rid of these ridiculous 4-6 year contracts that mean nothing except the size of possible transfer fee.
If you want a player under contract from another club, then trade for him with other players. No other fees involved. So if you want a clubs star player like Coutinho with Barcelona, Barce would have to give Liverpool a player or players they would like in return, so say Rafinha and Alcacer with a high prospect youth.
Bring in salary caps worldwide that's rated by competition level/coefficient. For example the EPL/La Liga/Bundesliga/Serie A have a limit of say £100k p/w and Ligue 1/Primeira Ligue/Eredivisie have limit of £50k p/w and so on. Wage limits can rise and fall by performance of the clubs and players contracts that are signed have these increases and deductions included so no negotiations needed.
Bring in the Bundesliga matchday squad rules of 10 homegrown minimum out of 18 for every league. Keeps clubs playing there own countries players, less foreign influx.
Players cannot break contract, only be traded for another player(s) or wait for contract to run out. Contracts are only a maximum of 3 years. If agents are involved in contract negotiations then the player must pay any fee for them, not the club. Players cannot negotiate with another team until that contract is finished, so no pre contract agreements.
Just a few things that I think could help. Radical?