If I had to choose, I think I would say that portion control is my least favorite part of eating well. Let me be completely honest with you. I love eating. It's one reason I enjoy cooking and while eating in moderation is wonderful I often want to take it too far. Here are some of my methods I have used to reign my eating habits in.
1. Find out what your daily caloric intake should be. http://www.mypyramid.gov/mypyramid/index.aspx
This website is full of great information. Before someone introduced me to this website I thought everyone needed 2,000 calories irregardless of height, weight, and activity level. Now I realize how silly that was.
2. Use a smaller serving dish.
While I was in college my family bought new dishes. We compared them to our old dishes and noticed how much larger the dishes were. When I eat now I try to use the side serving plates so I won't over eat. I also do this with ice cream. When I was a teenager I would eat a whole bowl, now I use a tea cup or something else small.
3. Don't eat out of the bag!
Pour a serving size into a plate or bowl otherwise you won't know how much you're eating.
4. Always read the nutritional value.
A lot of the time you will be shocked at what the portion size really is. In some boxes that appear to be single serving you will notice that it is really a serving for two or three.