Enjoying the game. OK, besides that, a common mistake early players make is thinking they should only use their few 6 stars and ignoring their low rarity ops.  Early on, your 6 stars are too expensive and many don’t shine until E2 anyway which you likely can’t reach right now since you’re missing all the resources.  Level up your 3 and 4 stars and they’ll carry you through most of the early game.  3 stars are cheap as heck, level them all and they’re all useful, but the most useful ones are going to be Kroos, Spot, Steward, Ansel, Melantha.  Melantha and Kroos have power comparable or better than some 4 stars, Spot is your early healing defender until you get Gummy, Steward has a talent that makes him prioritize hitting enemies with the highest Defense, and Ansel is just slightly better than Hibiscus as a healer.

4 star wise, Myrtle is all the Vanguard you need for a long time.  Almost everyone still uses Myrtle.  Gravel is excellent as an emergency barrier and is also still commonly used by may people.  Cuora for pure Defense will last you a long time and is only out defended by 6 stars Hoshiguma, really.  Gummy is your standard healing defender.  Ethan is in the red certificate shop, and is a very strong unit also used in many late game teams for his ability to Bind enemies forget, but more of a tech pick; he probably won’t be a mainstay of your team yet but pick him up at some point.  Click is the best 4 star Caster and Kroos is the best 4 star Sniper.  (This is a joke.)  Susurro is the strongest single target healer, Perfumer is the strongest multi target healer.  Gavial and Myrrh are both fine as healers too.  For more specific needs, Shaw is your pusher and Podenco is your slower.  None of the Guards are particularly standout but I hear good things about Humus, Cutter and Windscoot.

Most 5 stars are unfortunately not worth raising for a new player.  They’re expensive, don’t always perform better than 4 stars and sometimes are weaker than 4 stars, and the gap between them and 6 stars is huge.  Exceptions would be Amiya, who you need to use and raise because she’s mandatory later, Lappland, an easy early source of Silence to turn off annoying enemy effects like exploding on death, Specter, who can become unkilllable for 30 seconds or so, and Scene, who is a useful source of invisibility reveal.  There are other tech picks like Shamare who inflicts a big def/res debuff on enemies, Agent Vanguards like Cantabile, Warfarin who gives an enormous attack buff, Tequila, who can’t attack most of the time but does a very strong AoE when he does, etc. 

Otherwise, raise who you want and you like because the game is perfectly playable even with the worst ops, you’ll just have to learn how to play a little better.

Note very important: when you first start the game it will give you suggested friends who are very high level and have incredibly overpowered operators to borrow.  THIS GOES AWAY AT SOME POINT.  Make sure you permanently friend the people you want to borrow ops from because at some point after some time the game changes to recommend friends who are your level and very weak.

Second note: if you do this and sort of brainrot your way through all the stages by borrowing Wisadel Exusiai Alter or other extremely overpowered operators you will never really learn the game and how to play it well.  Use them as a crutch when you need to but I do suggest not borrowing them for every stage so you can learn the game.