I think it would be a help if Itch did a wishlist function like on steam. I know you could do that by adding a game to a list but I don't think most people bother. An actual wishlist button would be nice, fast, easy, people would click it.
For instance with my game Dungeons of Mysteria I released the demo, got massive views, had quite a few people donating cash, loads of positive comments, people saying they could not wait for the full game and then when I released, very little happened(because itch gives a page a massive boost when its published but not when its released) but not many people added the game to any lists or followed me so they would not have been notified when I released the game. It almost feels like it would have been better to Delete the game page and recreate it when I made the finished game, so as to get the same front page boost(also seems like abusing a system)
For Balloonys adventure I didn't release a demo or publish the page before hand just published when it was finished but I did not expect as many sales for that as its more what you would expect to find free on mobile phone(but with ads) so I cannot say if it did better or worse :P
I think you also have to keep in mind the day of the week you release on. When are people more likely to see your game? you only have a few days where you are visible so may as well maximise those views.
animated gifs do well on twitter, images with a few seconds of action or something really cute(I am doing a zelda style game about cats so I got both of those covered)
clips need to be interesting from the start.
check out my trailer for Dungeons of mysteria Dungeons of Mysteria Trailer 2 - YouTube
It did not do very well because even though it goes lovely with the music, people are normally scrolling down twitter, reddit ect when they are on the loo, skiving at work ect so they often have the sound off, and they have a very limited time to scroll. If its not instantly eye catching they keep scrolling.