Awesome, it's always great to hear that I've inspired folks. I'm not a marketing guy or game publishing expert so I'm not sure how helpful I'll be, but here's what I can think of:

For making your game findable, use everything itch recommends -- thumbnail, screenshots, and tags. There's only a few dozen itch games tagged word-search so you might get a handful of players just by being on that list. Personally, I got initial traction for my book by sharing it in a puzzle-game discord where I was an existing user (mainly lurking and play-testing other people's games). Note that most places will either have rules against self-promotion or will be filled with spam, so you should mainly share via communities you have a connection to. Feel free to share it here on this thread when you're done.

Regarding landscape & portrait mode: 75% of downloads have been for the landscape version, which I imagine most folks want to play right in Chrome or Firefox's built-in annotators. But a printable version is nice to have too, as printable puzzle books are fairly rare on itch but there's a good-sized niche of folks interesting in them. Ideally, the printable version should be playable in black&white for folks like me who don't have a color printer at home.

In terms of game-design: If you're an amateur designer, err on the side of easier difficulty. An overly easy puzzle book can be a fun way to spend half an hour, but an overly hard one is frustrating and most people will quit. You can hedge your bets by putting hints in the back. And if your answers aren't as self-checking as 12 Word Searches, you'll want answers in the back too. And since some people find Rule Discovery frustrating, you might want a third section in the back that explains any unexplained rules. Check out Lok as a good example of this: https://letibus.itch.io/lok. In many cases, it is good to have a bunch of easy tutorial puzzles in your book in order to reinforce the mechanics in the player's mind and make rule-discovery more fair. (Don't make the player read your mind.) One way to design a hard-but-fair puzzles is to make it solvable in multiple ways -- for instance, in 12 Word Searches, you sometimes have a choice between searching the grid for plausible words or deciphering the clues and using those to determine what word you're searching for.

are there any helpful programs or sites you guys use to make these puzzles?