I'm so glad you asked! First, remove the outer leaves. Any that are loose or damaged come off. Then, trim off the stem end, which will make them easier to cut in half. Rinse the trimmed Brussels sprouts in a colander and place them under cold running water. These removes any of the dirt that might be between layers. Finally, give them a pat dry with a clean kitchen towel or paper towels (or spin them in a salad spinner. We want them to be nice and dry so they roast evenly and don't steam.