Sometimes I fall into that category, but not very often anymore. For me, I had to really, really want to lose weight. So much so that I was willing to give up the mindless eating and do anything to get the job done. So thoroughly examine yourself and find out if this is what you REALLY want right now in your life because sometimes it really isn't the right time.
But if it is, then Claire's suggestion would be the first step. Rid your house of everything that will sabotage you. And if you have kids, remember that they don't need junk food either.
Stock up on fruits, vegetables, lean meats, all the good stuff. If you must have ice cream occasionally, make it a kid's scoop at an ice cream shop. Start reading about others who have successfully managed to lose weight (try the Success section at 3FC), and pick something you can do for the rest of your life. Plan what you're going to eat in advance, and write it down. And start moving! Weight loss really is about eating less and moving more.
You will not be perfect all of the time, but if you pick yourself up after you fall, and get back to your program with the next meal rather than the next day (or week, or month), then you'll be ahead of the game. Sometimes it's two steps forward, and one back, but all those forward steps will help you succeed.