Veggies are awesome. I've kind of simplified my veggie shake but things I've tried before are:
It really depends on what type of shake you are looking for. Usually, I make a fruit/veggie shake with spinach, strawberries, 1/2 banana, water and ice.
I think frozen bananas and strawberries are awesome additions to shakes but if you want something on the less fruity side, I'd recommend something like the following:
Spinach, cucumbers, celery, carrots, 1/2 apple, some ginger and water. You could also try some lemon juice/lemon zest as well.
You can't out-exercise poor eating habits.