This is quite an endless topic !
There are a few videos on youtube on how to make an itch.io page looks more appealing, which will most likely help a lot, there are plenty of indie websites to promote our games like indiedb.
Another complement strategy is to have your own youtube channel and made promotional video, gameplay samples, etc and use youtube algorithm strategies to let people know about your game. Here again, plenty of videos on this topic (TubeBuddy channel for instance)
Finally, popular selling "gateways" like Steam, app stores, Epic store, GOG, ... can be use as marketing on their own just because they have millions of customers/users. Good reviews there & curators reviews could boost a game, then it spirals itself without any effort I guess.