I've learned that I am terrible at guessing when it comes to portions and calories. I am also forgetful of things I ate. I also am a nibbler and these little bites put me way over my calories for the day. An exciting thing I realized was that allowing myself to indulge in small sweets, a lollipop or square of chocolate, each day reduces my sugar cravings and some days I don't even feel the need for sugar or snacks.
A surprising thing I learned is that when I'm really motivated I burn a lot more calories than I would have thought. This means that I need to eat more. This may seem like a good thing, but it is very difficult balancing eating not enough and too much. This is something I am still working on.