If you eat different foods all the time, this can be more difficult determining how much you should eat as a serving. I found a chart that helps you have a vision of measurements for you food.
Keeping this in mind might be really shocking at first. There are many times I truly thought I was eating just one serving size of a food and later realize how much I was over-eating. If you can stick to smaller portions and eat multiple meals through the day, you won't feel as hungry within a week. I find it amazing how little food I can be satisfied with if I actually go the week or so watching what I eat. Stomachs shrink fairly easily :-) Unfortunately I'm talking about your organ inside your body...not the fat you want to get rid of on the outside!