If I can fault Toshinori for one thing as a mentor would be not putting his whole network of friends at Izuku's disposal from the start: Tsukauchi, Gran Torino, the Shields, maybe even Recovery Girl or Nighteye. They'd have helped him grow easier and safer.
There's only one that's made me write, draw, do trades, commission many artists, start a Discord server try and push it with everything I had, fail miserably, fade to obscurity, keep commissioning stuff, sporadically keep writing, and finally finding others that love it like me!