Have you done specific diets before? Depending on how you got on with those that will give people an idea of what advice to give. I did Cambridge a couple of years ago, got on really well with it at first, but hated every minute, and quite frankly was a moody ***** (the word was the one that means female dog, but apparently I'm not allowed to type that) whilst on it! (Was pleased to lose over 4 stone though!) VLCDs are for those with real self-discipline, which I only managed for 3-4 months and have since piled all of the weight and more back on (they ruin the metabolism (temporarily if you are lucky) so you have to be really careful coming off them - not do what I did and just stop!).
Slimming classes are really helpful to a lot of people, I just wish I could do one, but my working hours change week to week and make it almost impossible!
I'm doing Diet Chef (this time), but today is day 1, so I can't comment on it yet! It is very convenient, but that's all I'm qualified to say right now.
Good luck whatever you choose!