the game doesn't really have a time limit or lose condition, so you can't really go wrong.
but if you want a fast start:
- Save a bit of everything, grow a couple of every crop at first. make sure to check you have enough time left in the season when you plant (28 day long seasons).
- prioritize the community center, it gives a lot of perks and makes sure you engage with all the mechanics. aa a first timer you can get it by summer year 2 or so if you focus, year 1 if you are lucky/hardcore about it
- when fishing you can make the bobber move left or right as you cast it, which can get you hard to reach fishing spots\
- Upgrade your watering can first, ideally near the end of a season when you don't have crops that need watering.
- hoe mysterious ground spots
- if you befriend people they will give you stuff, usually stuff they like that you can use to make them like you even more. completing the daily quests makes them like you more and is usually more profitable than selling whatever they ask for. the prize ticket you get later on for those quests are very good.
- Pay attention to luck on the TV, it makes a big difference for mining and fishing, it doesn't effect farming item qualities or the contents of geodes though.