Foils?

[Rass]

what is the best and most economical way to store your foils so they won't curle up?

[MuggyWuggy]

I would say in the dark around 70 degrees

I've noticed it mainly happens when it heats up

I would also recommend perfect fits to stabilize the shape, normal sleeves are too big imo

[NyghtHawk]

Keep out of humidity. In a binder is best. Holds them flat with the weight.

[Rass]

Keep out of humidity. In a binder is best. Holds them flat with the weight.

One or two cards per pocket?

[NyghtHawk]

I always keep one. Multiples is probably ok but would have to be uniform how many in each pocket I guess to keep it flat. Plus you'd have to sleeve them all so they don't get ruined putting them in and out. That's why I always stuck to singles.