First of all, LOVE THIS GAME! Art is unique and nice, characters are great to look at (though didn't read much of the dialogue if I'm honest), neat premise, and lots of potential. Don't think I would have enjoyed it if I found it much sooner though as updates are slow.
Now, I 100% what's there in the 0.19D build so I'm going to give a few tips for where I got stuck because I was having a hard time finding some stuff.
End of Day 2, the Rabbit:
To end day 2, you need to find the rabbit in the garden maze. For me, I didn't finish this and saved and came back to it later. There are no tasks for this so I ended up running around a LOT and inflated my play time. The only reason I found what to do is I joined the Discord and scrolled through the release notes.
What to do:
The garden maze's second screen has four paths, N, W, S, and E. W and E just loop you back.
Starting from the Fountain, move into the garden, then move E, E, S, N.
You don't have to do it in this order. You need only find the rabbit near the appropriate exit. Eventually it will take you to a new area, a scene, and the end of Day 2.
Note: I don't know if there are any missables because I ended up doing everything I could until Day 3 so be warned but you'll get the same warning in game.
Dialogue can be repeated with new results:
A number of the dialogue options can be repeated. Most scenes when repeated this way well have additional content. The one that got me was Monique's "Camera" dialogue. Once you've found enough oddities, this option will give some more scenes. You don't click on the monitors!
Get the fish hook from Jeane:
You can't get everything from the three fishing spots until you have the bigger fishing hook. Get it asap. You get infinite coins from the fishing mini games so don't worry about spending coins.
Similarly, don't be afraid to buy and use dynamite for the same reason. You need dynamite for the storage room fishing spot but it makes every fishing spot easier.
Oddities locations:
You can get hints in the awards menu for this so it shouldn't be too difficult to find them. You just won't know if you can find them at the point in the game you are so hopefully this helps.
Eye in the hallway: There is a red eye that appears in the ceiling between the main entrance and the storage bay. This is this hall with the janitor's closet and board.
Ghost in the Window: In the Gardens screen (not the maze) you can see a ghost at the top of the screen. I hate this one because I don't think it's animated like every other oddity.
The rest: I don't remember what the rest are called and don't feel like looking it up but they are more obvious. Saw in the tool shed, footprints in the infirmary, and ghost shadow in the men's stall. Probably forgetting some.
How to unlock the last two characters:
Reach Day three and they will be standing there. I spent a LOT of time trying to unlock them and the admin room because of the gallery hints not making it clear. After you find the rabbit though (my hint above) you can't miss these characters.
Thats all for now!