Getting the game and demo up on Steam was more convoluted than I expected. If you make any errors, no matter how slight, you'll have to wait for Steam Support to notify you so you can fix the problems and resubmit your software and store-page content.
I found the following tutorial very helpful:
https://www.youtube.com/watch?v=gwMPvEFFomE
Another thing that I didn't anticipate is your capsule art needs to be designed so that the demo banner doesn't obscure your logo or text. Not an issue if you aren't hosting a demo, but something to keep in mind if you may want to make a demo available later.
While I haven't heard of Steam pushing your visibility upon making a coming soon page, I did have a big spike in traffic the following day. A lot of this traffic was from within Steam.
Considering I had my nose to the grindstone while making the game I didn't do much to raise awareness that it even existed. I have been accumulating wishlists over the past 5 days ranging from 3-12 per day. My "marketing" efforts have simply been posting here and in a few Reddit forums. Strangely, I currently have more wishlists than I do demo plays. I would have figured people willing to wishlist would try the demo to see if they did indeed like the game.
As far as the demo goes, people tend to quit playing very quickly or keep going until they've likely completed all the included levels. There aren't many instances between those two extremes.
How has everyone else's experience on Steam been?