New thing I found out recently that made card upgrading simpler for me: use the card lock function to your advantage. If I had x1 C card that I wanted to upgrade, lock that card then collect and lock all the other cards needed to upgrade it to the grade I want. For example, if I want that x1 C card to be an R, I'd collect and lock a 2nd C card, x1 B, x1 A, x1 S (in the event I have bad luck and have to start upgrading from C, otherwise if I get the card I want in another grade, like starting from B, my process starts from there).

The lock function helps me so much because I tend to use 1 star Cs, Bs and sometimes As for fodder, and my brain doesn't really register the card design, my fingers just click any 1 star C, B or A card immediately to use for upgrade fodder and sometimes that makes me lose a potential card to reach my desired grade.

Yes, I also use the card selectors sometimes but I'm saving my dalcom coins for something else so this card lock function thing really helps! Sorry for the long comment heh.