The way I'm doing it is counting every single calorie that goes into my mouth, and keeping the daily total below a specified number - in my case, 1,200 calories. I'm trying to maintain a balance of protein, carbs, vegetables, and even fat, which is needed to metabolize some vitamins.
So if I have 260 calories at breakfast and 500 at lunch, I know I can spend 440 on dinner. I don't really feel hungry most of the time. I haven't had one sugary drink, one cookie, one cupcake or two pieces of candy since I started. (I picked up a butterscotch candy at a booth at NAMM, started to suck on it, and it was too sweet. I threw it away.)