For fall and winter veggies, what we grow falls into two main categories: greens and roots. Let’s talk about greens: within that category, you can think of the greens as being either salad greens or cooking greens.
For salad greens (arugula, lettuce, spinach), you can take scissors or a paring knife and cut all of the leaves 1-3 inches above the soil surface. Instead of pulling those roots out, leave the cut plants in the soil to see if they grow another crop (they often will!).
For the cooking greens (chard, collards, kale), you want to harvest the outer, larger leaves while leaving the smaller inner ones to continue to grow. You can use scissors, a small knife, or your hands to pinch off these outer leaves. Both salad and cooking greens are often referred to as “cut-and-come-again” plants, but the cooking greens typically bounce back much faster and stronger than the salad greens.