How do you categorize your photocards?

I'm fairly new to the kpop community and I know a big collectors item is photocards. GD's new merch is the first kpop merch I've bought which includes photocards. I know a lot of people keep them in binders but my question is do you guys buy multiple binders, and if so, how do you categorize them? Do you do it by gender, by group, or do you just keep all your photocards in one binder? I also see that people who do use binders decorate them really cute, I've heard a lot of people on Instagram will buy and customize you a binder so if so can anyone recommend some people I'd appreciate it. ☺️