There are a lot of good substitutes on the market. I think you should start with one thing and shop around for healthy alternatives to try. Take it slow and don't beat your self up when you make a mistake. I remember I used to drink a 2 liter a day...of soda. then I got on diet soda and now I really don't drink it at all. Took 5 years total but hey!
Fatty foods have always been one of my triggers ;). Remember not all fats are bad. Peanut Butter, avocados, nuts, coconut oil and fish oils are good for you. Personally I have found that swapping the fatty foods for something crunchy dipped in peanut butter or in an avocado dip, or a thai curry paste (something with lots of flavor! ) makes the cravings much less.