Step One: We are going to do a quick calculation of how many calories you take in daily. Write down all the foods you eat from breakfast to dinner and everything in between. Be honest. I can't stress this enough. If you are not honest with yourself then you will not get the fast results that you want.
Step Two: Get that list handy of what you eat on a daily basis. Sort them from fattiest down to healthiest.
Step Three: Take the fatty foods that you have been eating or drinking and substitute them with a healthy alternative. So instead of eating a cheeseburger from some fast food place make your self a ham sandwich or a salad for lunch.
Step Four: Make a plan and try to stick to it. Here is what you are going to do. The night before write down the exact foods you are going to eat for each meal. Make sure you plan out your snacks too. If life happens then don't get discouraged because there is always tomorrow that you can start your plan all over again.
Step Five. This is the biggest and most beneficial step of all of them. And it is portion control. I suggest that you slowly take down the amount of food you eat on a daily basis by one eighth every day for 5 days. This way you won't starve yourself into eating unhealthy.
Following the steps listed above will get you on the right track and right state of mind. Most people fail at diets because they don't plan or because life happens. If you don't follow the plan one day then just make sure you start it again on the next day. The most important part of all of this is that you cannot give up. Make it up in your mind that failure is not an option and that you are going to lose weight no matter what sacrifices you have to make.