Here are the things that made a huge difference for me:
1) I stopped eating fast food and I stopped drinking diet soda. I drink a TON of water now. Once I broke the habit of FF and soda, I found that I don't really even like them. I still steal a few fries of my brother's meals, but the couple of times that I ordered a french fry myself... I've found that they don't really even taste that good anymore. Same for soda -- too bubbly and chemically tasting.
2) I ordered food through an online company (BistroMD) that retrained my habits regarding salt, sugar, portion size, and eating more veggies and lean protein. I'm no longer ordering the food, but my habits are ingrained and, for the most part, I have no desire to eat the way I used to eat. The meal plan also forced me to eat actual meals throughout the day, instead of grazing.
3) I eat breakfast!! Plus lunch, dinner and 2 snacks.
4) I log everything I eat and count calories. It takes a lot of effort at first, but eventually becomes 2nd nature and easier too when you have memorized the calories for the things you eat the most.
5) I consider this a total lifestyle change, not a diet. I allow myself indulgences occasionally and know that I'm creating habits to last me. I will not reach an end-point where I can stop and go back to my old ways. I'm okay with that.
6) I eat LOTS and LOTS of veggies -- frozen and fresh. They add bulk with few calories. Besides, they're just plain good for you!
Best of luck! There's TONS of helpful info and advice on the boards here. These chickies are super friendly and supportive!