Diet, Diet, Diet!! Losing weight is no fun and can be very defeating. But staying motivated and dedicated will help you persevere in the end. Your diet is the most important factor in weight loss. I recommend eating smaller portions, but eating more often. Focus on variation as well as low fat and low carbohydrate foods, as in the MyPyramid.
Exercising or staying physically active should be your second main focus. If you are sitting for more than thirty minutes at any one setting, you are doing something wrong. I understand that your everyday life makes it difficult to do so, but do the best you can and go from there.
I also recommend hitting the cardio for at least an hour a day for five days a week. Before cardio, hit the weights for a total body weight training session to deplete the glycogen stores to help burn fat during your bout of cardio. Below is a total body work-out that you can follow. I recommend hitting the weights three days a week right before you do cardio. Try and hit two set of 20 repetitions. Good luck!!