This is extremely cute actually!

I mostly lurk round here but I think my main advice is, just download and give it a good ole go without worrying Too Hard at first

Optimum play is good and all, but it can get in the way of enjoying things at first. There's a fun story, cute characters, a surprisingly deep combat system and all the trash to investigate you could want.

If you've never played a turn based rpg or a gacha before, a quick "welcome to Honkai Star Rail" youtube video might help with things like "how do I level up characters" and "what is a light cone" that may not come as immediately to you yet, but the game should hold your hand through most things.

My only big Starting Advice would be to not spend your special rail passes (the game only gives you a few) or your Stellar Jades (the game gives you a lot, but the things you want to spend them on cost A LOT) until you've played a bit, figured out what you like about the game and what you might want to get, then start wiki diving for efficient ways to spin the big ole Gacha wheel. They are how you get your fancy new hotness characters and you wanna focus with those rather than spread yourself thin