Before roasting, I generally season my vegetables with salt, pepper, some form of garlic, olive oil (1-2 Tbsp), and balsamic or red wine vinegar. I pre-heat the oven to any temperature above 450 and give the veggies a shake or stir about about halfway through to ensure even roasting.
There are several options as far as the actual cooking goes. If I have a large amount of veggies to roast, and especially if I am including some particularly hearty veggies like turnips, I use a roasting pan with a little water in the bottom. In this case, cooking time can last anywhere from 40 minutes to over an hour. (I do several taste tests to make sure it is tender enough before I take it out of the oven).
When I have fewer and less durable veggies to roast such as cauliflower, broccoli, and/or thinly sliced carrots, I just toss them in a bowl with their seasonings and oil, throw the whole thing onto a foil-covered cookie sheet, and turn the heat up as far as it goes. This method can take as little as 7 to 15 minutes (and needs constant vigilance because it may inspire the smoke detector to go off), and again, it involves several rounds of taste-testing.