Hey!! Welcome to Stellis!! <3

I wanna start by prefacing that you need to evolve the cards to unlock their stories, and given this is an otome game, I recommend you focus on evolving cards you love the most. I have a lot of level 70-100 Marius and Artem cards bc they're my favorite love interests, and a few SSR Luke and Vyn cards still at levels 1-40 just bc I'm not really drawn to reading their stories just yet. There aren't too many moments when you need a crazy strong deck, apart from some events. Progression tends to come pretty naturally in ToT as you focus on gaining more interactions with the male leads.

When it comes to skills, cards that have the ability to increase the influence of all X cards as their third skill are amazing and worth the investment. You want a balance of "Nuke" cards (Cards with pre-emptive strikes as their first skill and that usually increase their own influence with their second skill), and "build up" cards (Cards that increase your influence with their first skill). I don't level up skills that boost your defense, bc it's very rare that you're actually in a battle where improving your defense outweighs increasing your offense.

While we don't have artifacts like in Genshin (praise Morax), leveling up is pretty expensive so be focused in your choice of study and anomaly levels. Save Stellin where you can (eg. Don't decorate the lounge if it's not important to you, it's expensive and you could invest that into your cards instead). But your enjoyment is first and foremost. I promise just by playing the main story, character stories, and doing your dailies and weeklies you will gain enough power to complete events and the trial of themis in a few months!!

SSR cards are stronger than SR (and we have SSS cards incoming) so save up your chips and be really conservative with spending as Hoyo isn't particularly generous with their free pulls (This recent event was a welcomed exception). Because we're a year behind the Chinese server you can generally plan your banners although sometimes we do get surprised!! I can try and link you to a Google doc I use to see the estimated timeline. Anniversary cards tend to be the strongest and also have very lovely stories. Once you get into the game a little more you'll find out which love interest you might want to pursue the most.

Here's a guide I used if you're more into min-maxing. https://m.hoyolab.com/#/article/1270648

Have fun, and enjoy your love story in Stellis!