I'm another saying that permanent changes are more suitable than "diets" (it's just unhelpful we use the same word for "weight-loss programme" as "how do you eat regularly").
In your shoes I would start by looking at why I was overweight...keep a food diary to see where the excess calories are coming from. You might think it's obvious, but even if you exclude the obvious you might find your calorie intake is still too high.
Related to this is exploring what motivates the eating...hunger, boredom, habit, emotion etc. and start practising mindful eating - thinking about what you're eating and why each time you put food in your mouth. A useful trick here is to think about whether it's a mealtime, and if not to consider not eating for 20 minutes after you first think of eating something. If you still want to eat after the 20 minutes, have a small, healthy snack. Most of the time you'll probably have forgotten about eating after the 20 minutes though.
The next step is portion control. If budget allows, get a few healthy eating meals from M&S (decent quality) and see how much food you get in a 400 cal meal. This is about the right amount when you add a drink and desert of some kind. People are often shocked how little this looks but it's a great visual to show what a portion should look like (particularly pasta!)
The final aspect is not to have any banned foods as this more than anything else makes people obsess about food. Allow yourself to eat any type of food you want, but limit the amount of that food. I maintain a healthy weight (size 8-10) but have a glass of wine and some chocolate every day. It's just a small glass and 4 x individual good quality chocolates (needs to be good quality as cheap chocolate has too much sugar).
Exercise is also important as it boosts the metabolism as well as having MH benefits, but as pp have said, most people don't have the time to outrun a bad diet.