Yes, save the primogems and fates until there’s a character that you really want in the respective banners. Some quick facts about how the wishing system works:
Every ten rolls you will get a four star or five star weapon or character, the ten rolls reset when you get the four star.
Every ninety rolls you will get a character that’s a part of the banner, the count to ninety will reset when you get a banner character.
If you do not get a banner character then you will get the five star on your next ninety roll.
I hope this makes sense when you start playing. Outside of the Wish system.
Artifacts are VERY important, they are arguably more important than leveling the character themself.
Do not invest into a lot of characters, you will run out of materials.
Sekapoko has pretty accurate information about the game on YouTube. If they don’t help then feel free to message me through psn (if you use playstation) at Nebulous Vendragon, just let me know who you are so I don’t ignore you lol.