The first week can be tough. You may feel hungry and ill. However, by day 5 or 6 you will be in ketosis and your hunger will be supressed and you'll feel a lot better. Stick at it!
Drink plenty of water - it speeds up your weight loss. At least 3 litres a day.
Try all of the foodpacks. Some you'll love and some you'll hate but everyone's tastes are different.
Ask questions on the forum whenever you're unsure of anything (you don't need to be told this as you've already started asking questions!)
Make the most of your group therepy sessions. These sessions are essential if you hope to keep the weight off afterwards.
Never skip packs. Once you are in ketosis you won't feel very hungry and may be tempted to have 3 packs instead of 4. You won't lose weight any quicker, infact it'll be slower as your body will be in starvation mode. In addition, you need 4 packs to get the vitamins at you need and also to have the right amount of protein. If you don't eat enough protein you will get muscle wastage which is not the result you want. Having 4 packs a day you are fine.
That's all I can think off for now!