I had a similar habit when I regularly ate at a cafeteria:

• Fill half the plate with salad
• Put other food on the other half of the plate

I usually ate the salad first (and at all), because I have a strong habit of leaving the best for last (and, perhaps unfortunately, of cleaning my plate). This had the secondary effect that there was only half a plate available for calorie-dense foods, and I probably ate fewer calories overall because of it.

It helps, though, that I actually enjoy eating vegetables as long as they're well prepared.