Some things on itch.io you can use:
1. post your game in release announcements. Not exactly sure, but this seems tied to whether or not your game goes in the "fresh games" section of the front page
2. make devlogs for updates and releases and whatever else you'd like
3. join game jams where your game will get some notice
4. make your itch.io page look really fancy. This will be one of the first things a potential player will see so it's good to make sure it looks amazing. Depending on what you want to do, custom css might help
I hope this is helpful to you :) it's just what I have learned from making games here