First thing, do the food reflection. Do it and do it and do it and do it. The second thing ishaving little tricks when you eat. One of the tricks to use is, never go back for seconds. Measure what you want the first time. Measure, put it on your plate, walk away and never go back for seconds. It's an interesting one.
But how do you understand how much you need? The first day, you go with what you have taken and it might not be enough the first time. Okay, you may be a little hungry before the next meal, but the next meal is only 4 to 6 hours away, you won't starve to death. So, take what you need and if it's not enough then tomorrow, remember how big the size was, and take a little more.
Try to get a picture of the size of the plate and what you take, of vegetables, protein, whatever it is. Try to get mental pictures of how you put it on your plate and how much of each item you're taking. The more you get that picture, then the better you get at taking exactly the right amount. After many years of doin this type of practice, say, for me, when I go to get my food, I'm putting a kind of picture on my plate. I have an idea of how much food I need, how much protein I need, how much vegetables and so on. After a while it becomes more of a mental picture and I just follow that picture and I know that will be enough food for me. That's a little trick to use.
Another thing to do is to reflect on the Dukkha that arises from greed for food. Reflect on Dukkha. It's painful. It's painful mentally, because we become a slave to our desires. And this doesn't just work with food, but with greed and desire, for any kind of outward grasping. It's the same sort of thing, to reflect on the Dukkha that comes from wanting.
Sometimes our desires can be like an empty pit, the more we get the more we want, it's never enough. So to reflect on the Dukkha that comes from desire whether it's food or whether it's anything. The food reflection we teach before eating, in particular, why do you eat? Can you actually keep that in mind? Why? The main reason for eating is to keep the body alive, to keep it strong and healthy.
So the more effort you put into the food reflection, the more you try to guard against taking too much, then the more you stop going back for seconds. These things will definitely help to reduce your greed regarding food.