Turning a poor standard league into a brilliant one

As the title says, I'm looking to use the editor to turn a league of poor standard (the Welsh Premier) into a world class one. I've tried this before without any real luck, and was wondering what pointers anyone could give if they've tried this before. My current plan is to edit the following

-each club's reputation, finances and facilities
-the league's reputation
-the country's reputation

I'm wondering whether I've left anything out that someone knows of? Not going to bother changing CA and PA of each player, but will instead probably wipe each team clean of staff so that the game automatically fills them with regens of top quality. If anyone could lend a hand with some suggestions, I'd really appreciate it!