supplements & V8 won't get you what you need, bottom line.
it's a good idea to eat both raw (ie salad) and cooked veggies. raw veggies have enzymes & other stuff that heat destroys, while cooking releases many micronutrients in veggies.
prefer fresh over frozen, and frozen over canned. if you cook frozen, try not to add water (ignore the directions) -- put a little oil or butter on the bottom of the pan and stir them just enough to keep stuff on the bottom from burning. adding liquid that you'll drain off later just drains away nutrients. the canning process brutally destroys stuff, and the varieties of veggies that stand up well to being canned are generally the least nutritious varieties.
that makes it sound difficult, but with a few rules of thumb, it's not.