What activities should I do every day?

I'm newly back into the game with a lvl20. What activities are time-gated? In other words, what activities benefit from doing them repeatedly every day or every few hours. Activities that I otherwise would look back on two weeks from now and say, "I wish I had started this before."

Outside of the holiday events and some special collabs everything is always there to do.

Do seasonal events at least once while they're available- for example, The Rising event that's on right now won't ever be coming back. But outside of that do your roulettes in Duty Finder once you unlock them for the rewards (resets daily) and check your challenge log for goals that reset every week (you can unlock this feature in Limsa Lominsa).

Crafting beast tribes are a good bet. GC turn ins are well worth it over time as well.

Unlock your challenge logbook f you haven't.
Hit up the Gold Saucer.

Otherwise at your level, just keep earning exp.

There arent a ton of daily reset activities. Crafting turn ins, beast tribe quests, mini-cactpot, and roulette rewards are all i can think of. As a lower level character you dont have access to the beast tribes yet, and the roulette rewards are more meaningful at higher levels. Cactpot is just for MGP, so your mileage may vary. If/when you start crafting, by all means start doing your dailies as soon as its feasible. Otherwise these mostly start to kick in later. But Canadanes advice about the challenge log is good. That one is on a weekly timer, but theres lots of rewards in there that are worth pursuing.

Edit: I remembered two more. Harvesting treasure maps and squadron missions. Still not low level activities, but they have an 18 hour timer.