If you have a typical salad spinner, Kristen Miglore at Food52 suggests you use it as an all-encompassing salad prep and storage tool:
Wash and spin your lettuces, then stick the whole contraption in the fridge, lid and all. You can wash your greens right in the spinner by filling the cavity with water, swishing the leaves around to shake off stubborn grit, then lifting out the basket to drain off the sooty water… There’s enough moisture left pooled in the bottom of the spinner to keep the leaves hydrated and prevent them from withering, but not enough to sit on their surface and inspire rot.
Miglore explains that this method has allowed her spinach, arugula and lettuce to avoid wilting for up to a month at a time. Considering that it hardly ever takes that long to eat up a batch of greens, that’s more than enough time for effective storage. The downsides, of course, are that your salad spinner is unusable and it takes up a lot of space in your fridge. Just don’t forget to keep the lid on; that’s the most important part.