The best thing since the salad bar is salad in bags. Already washed (so you don't have to) and cut into bite-size pieces (so you don't have to), it comes premixed with several varieties of lettuce. But you might prefer to buy separate bags of greens and then mix your own. Here's why: The more interesting store blends combine fragile greens with hearty ones. And, unfortunately, they don't stay fresh for the same length of time. When one dainty leaf goes bad, it can turn the whole bag against you.

One formula for the healthiest greens (they're the darkest in color) with the most flavor (a blend of mild and peppery), as well as the greatest shelf life: Combine two handfuls of bagged romaine with one handful of bagged watercress and one of bagged spinach.