Do you really need to eat that or are you just bored?
I ask myself this at least once a day. The answer is more often than not, "I'm bored." So I grab some water and go do a couple sit ups. That fixes my urge to eat something every time. Asking yourself if you are just reaching for a snack because you are bored is a great way to control mindless eating because it automatically holds you accountable for something. Most people, when confronted by the question will feel a little guilty about getting a snack and then will just put it down. Sometimes a little bit of guilt is a good thing. And wouldn't you rather feel guilty about a snack before it has touched your lips than after you've already eaten it?
If water and sit ups don't work for you, try this. (Don't laugh at me, but I heard this tip from Pamela Anderson a few years ago.) Brush your teeth. Mint is a natural appetite suppressant. When your mouth tastes like mint, your don't want to eat peanut butter or Doritos. Following this theory, mouthwash, strong mint floss, and Altoids should also do the trick of getting enough peppermint oil swirling in your mouth to make you not want to eat. A couple of good peppermint candies after dinner should do the trick of satisfying a sweet tooth and not have you munching away on brownies. (This tip will not work if your body is actually craving nutrition like a solid, balanced meal.)
Out of Sight, Out of Mind. Keep snacks stored away in cupboards or behind a closed door and not on the counters. When you see something out you are more likely to grab and munch than if you have to search for it. Instead of having chips and bakery items out, keep fruit on the counter. You'll be amazed at how much more fruit you eat. But don't buy fruit just to buy it, if you don't like something it will sit there until it rots. My favorite things to have on the counter are bananas and a bowl of washed grapes because they are cheap and easy to grab/eat. Also, clementines are season which means these intense, juicy cousins of the orange are only about $5 for 5 lb. They are easy to peel, have very little pith, and no seeds. You are much more likely to eat a couple of these than a regular orange.
Pay attention to your liquids. We all know alcohol has a good amount of calories, but I am talking about drinks that you have throughout the day. Sodas are the epitome of empty calories. They are loaded with sugar that does nothing for your body, and those simple carbohydrates are easily converted to fat. I am not going to tell you that fruit juice is bad because it isn't... when drunk in moderation. Cranberry juice and orange juice contain lots of things that are good for you, but they have natural sugars. An 8 oz glass of all natural, no sugar added fruit juice can have up to 120 calories. And even worse, drinks like processed lemonades and fruit flavored drinks can have just as many calories in 8 oz, but no good-for-you things. My suggestion? Crystal Light (or equivalent). I would say water, but I am one who easily tires of water and I need variety. Sugar free drink mixes are cheap and have 5-10 calories per 8 oz serving (if you make them to suggested strength). I like lightly flavored water, so I dilute mine to half the original, which means only about 3-5 calories per serving. They even have ones now that have added vitamins and fiber.