If you smoke, quit. This is more important than your fitness goals. Enlist your physician (MD, and DO in the US) to help.
See your physician before starting your diet and exercise program, for clearance and advice. Make sure you are caught up with recommended preventative measures, and that you are compliant with taking your medications as prescribed.
If you drink alcohol, drink only in moderation, meaning one serving for women, and up to two for men. If you have a problem with overindulgence or addiction to any substance, get help, starting by talking to your physician. You may want to stop drinking while you have weight to lose, since it adds calories.
Eat breakfast. Eating breakfast improves your performance in mental tasks during the day, when you are likely to be working. People who eat breakfast tend to eat less during the day, and lose more weight than those who don’t.
Consider trying to have a source of protein with every meal, it may make you less hungry afterwards.
Try eating three meals a day with no snacks in between. It goes against the latest six small meal a day fad, but it is our traditional cultural pattern. You get to have three decent meals, rather than several micro-feedings during that day. If you find that you get ravenous at some point during the day, or that you can’t make it through a workout, a snack may be warranted.
Watch out for calorie bombs, which may be different for everyone. Sodas with sugar or HFCS, fruit juices or drinks, cakes, pies, cookies, ice cream, other deserts, chips, crackers, popcorn, donuts, muffins, bagels, big bowls of pasta, fast food meals, Chinese take out, pizza. They either have too many calories, or you might tend to eat more of them than reasonable.
Avoid calorie poisoning, also known as over-nutrition, which is taking in more energy than you burn. You can do this with three traditional meals containing reasonable portions, combined with a moderate exercise program.
Get some exercise, meaning resistance training and stretching at least twice per week, and some moderate physical activity for 30-90 minutes at least five days per week. Vigorous cardio for at least 20 minutes three times per week can be substituted for the moderate physical activity.
Be accountable, somehow, to someone. Measure and track what you are doing, along with your progress. It will be a slow journey, and you will make mistakes. But if you look at what you are doing, you have the opportunity to change and improve. Consider starting a blog like this one, and if you do, please send me your link!