In the fridge in the original bag with as much air removed from bag as possible.
If they have been in there to where they look like they might get dried out or past their exp date I stick them in the freezer inside a freezer zip bag.
For flour (not corn) tortillas in the freezer:
I traced around plates the same size as the tortillas on cereal bag liners and cut them out and put them in between each so I can take out whatever number I need without them sticking to each other. (Save the circles for future use.)