When roasting several different types of vegetables at the same time, be sure to cut them in uniform pieces so they cook evenly. Cut denser vegetables such as carrots and potatoes into smaller pieces so everything's done at the same time.
Roast veggies in a foil-lined, heavy, shallow-sided roasting pan, like a jelly roll pan. If the pan is too small, veggies will steam, and you want them to be crisp.
Coat foil with cooking spray to keep veggies from sticking. Then spread them out! Vegetables roast best in a single layer, not crowded.
Coat veggies with a little Italian salad dressing, butter or olive oil, and let your creativity take over by trying different herbs or seasonings. Recently, I coated veggies with olive oil, then sprinkled on lemon-pepper seasoning, Italian seasoning, salt and pepper. Before baking, I give them a quick toss.
To promote uniform browning, I usually stir the veggies once, about halfway through cooking.
Vegetables are done with they're tender and easily pierced with a fork or knife.