Their first step needs to be immediately putting a halt to changing masteries every season. While this makes things "fresher" it most certainly is annoying to find certain things broken (perseverance needed the nerf, and I felt this immediately). Don't get me wrong, I love innovating and being one of the first to spot things when it comes to theory crafting, it does nothing for the health of the game if they continuously shift the meta to a different 10% of champion pools.
Their second step is (and sorry to say this) that they need to STOP making new champions at a rapid pace, or altogether until they shut down the FoTM problem. Right now, they have accomplished this slightly but it seems to be always something game breakingly broken (hello Yasuo / Braum walls), and creating a much more frustrating experience. Honestly, we have enough champions right now, and not enough of them are even in a good spot. Again, when I say not enough, I mean 90% of champions are being thrown out of the meta and becoming unviable. We all have expressed this concern with lackluster same boring picks (except Voyboy, love him) from LCS, but the concern is much more dire.
Sadly, the only thing from Riot I have felt been doing an amazing job has been the visual updates / clarity team. I understand game play is a hard shell to crack, but this has been an ongoing problem for years and needs to be solved before people just shift to another MOBA. The more champions they add, the bigger the problem is just going to get.
It's not just about bans, but the problem with the FoTM train being 10% of the champion roster. It just doesn't help with new champions like Yasuo and Braum making life a living hell with a broken game mechanic that effectively nullifies SO many champion abilities with one good wall.
To me, right now, League honestly is about FoTM and effectively ruining someone else's experience from one simple pick. Infuriating, and not innovative. This is from someone who loves LoL.