Here is a list of candidate items for roasting:
Onions:30 to 40 minutes
Tomatoes: 15 to 20 minutes
Squash: (butternut, acorn, etc...) 20 to 60 minutes depending on how small they are cut
Root Vegetables: (potatoes, beets, carrots) 30 t0 45 minutes
Soft Vegetables: (zucchini, bell peppers, summer squash) 10 to 20 minutes
Thin Vegetables: (green beans, asparagus) 10 to 20 minutes
Cruciferous: (broccoli, cauliflower, brussel sprouts) 15 to 25 minutes
Once the vegetables have been cut down to serving sized pieces, coat them in oil. Be generous, but not to the point that they're swimming in the pan. It's also a good idea to rub them by hand with the oil to ensure an even coating on all of them - don't be shy about getting your hands oily.
Toss the vegetables with a bit of salt - sea salt or himalayan salts are nice. Now is the time to add other seasonings as well... Thyme, rosemary, etc...
Space the vegetables out on the pan - too close and they will simply steam themselves. We want to have a nice roast to them so spreading them apart is ideal.
Remember that a softer vegetable will often cook more quickly than a harder vegetable. Smaller pieces will also cook more quickly.
Roast the vegetables until they are tender enough that a fork will pierce them easily - you may see some charred bits on the edges which is also nice - these add a nice flavor to the vegetables so even if the vegetable starts to become soft you may want to keep it going an extra 5 or 10 minutes until you begin to see the char begin.