There are no gimmicks. "Going on a diet" might help you lose weight for a while, but you'll gain it back after you get off the "diet". What you need to do is to change your diet, and generally to change your lifestyle.
For most people, the real challenge is motivation - why do you want to lose weight? Is it a means to an end, or is it an end in itself? For instance, if you want to lose weight so you can go backpacking (less body weight to move around means less energy spent means can go longer distances; also means joints like knees don't wear out as quickly) you can focus your goal on that, rather than saying "I'd like to lose 10 pounds." Or if you're less outdoorsy and more inclined to competitive motor sports, you can think of each pound you lose as a fraction of a second off your lap time (or quarter mile, depending on your preference).
For most people, the real challenge is motivation - why do you want to lose weight? Is it a means to an end, or is it an end in itself? For instance, if you want to lose weight so you can go backpacking (less body weight to move around means less energy spent means can go longer distances; also means joints like knees don't wear out as quickly) you can focus your goal on that, rather than saying "I'd like to lose 10 pounds." Or if you're less outdoorsy and more inclined to competitive motor sports, you can think of each pound you lose as a fraction of a second off your lap time (or quarter mile, depending on your preference).