Exercise, just simple walking.
Limiting the amount of food you eat.
Some medications cause weight gain.
Drink more water.
Food intake - small portions, not too near bed time, low fat foods. You dont need to diet, just eat the right foods - theres no need to go hungry. You need to be disciplined - its a habit. Just like you can get into the habit of eating to wrong food, you can get into the habit of eating the right food.
Exercise - the more you do the better. If you can do an intense 1hr / day, with the right diet, you will see results very quickly.
Basically, you need to burn off more calories, than you take in - then you'll lose weight. If you get your diet right, it'll stay off for good.
I don't believe in only eating veggies an fruits. You can honestly eat whatever you want, just need to cut the size down. A little of something is never too bad. Along with working out (even if thats only walking around the block a few times) It evens itself out. And drinking lots of water or gatorade.