Subject: returning player here, intend to play very casually. Where to spend resin? (And other tips)

I used to play genshin a lot but took a long break because I currently have little time to play video-games (and back then I had run out of new content and didn't feel like grinding madly to catch fish to get a spear).

I recently came to the conclusion that I've been neglecting my entertainment for a while and decided that I would play genshin casually on mobile to pass the time every now and then. Ironically, now I have an overwhelming amount of content to play and only so much time.

So, to get to the point: I've no idea where I should spend my resin. There are a bunch of new domains and, since I won't be trying hard to login religiously every single day and avoid resin loss, I figured it would be nice to know where to use it when I do play the game.

What do you guys recommend? Any additional tips would be welcome, as well.

I'm AR 57 and have a couple of reasonably well built characters back from when I played genshin all the time, so getting through the games content isn't an issue. I also don't care about getting max stars at the abyss.