Don’t worry too much about missing things, it’s not that kind of game. Feel free to try vibe-based and experimental stuff, it’s not a difficult game. I would avoid the wiki until you feel you need it. However, here are things I would have liked to know when I started.

1. Watch TV every day. You can get recipes from the cooking show and useful info from the other channels. Although this is less important now apparently.
2. You can give people 2 gifts a week, one per day. Everybody resets on the new week.
3. Seasons have 28 days, not 30. Don’t plant things that you won’t be able to harvest by day 28.
4. I would recommend the four corners farm, even for single-player. Each of the corners has it’s own specialty so you get a little bit of everything.
5. Don’t buy a Jojamart membership, lol. This starts the corporate path.

Edit: Somebody else mentioned that if you don’t like a specific part of the gameplay (fishing, etc.) you don’t have to do it. I would like to emphasize this.

Edit2: They added big chests? Damn, maybe I should also get back into it.