Yeah like stated above, atleast downsizing one size would be a great achievement! The last thing you would want is to lose so much weight in the space of 2 months and be left with dull liveless skin, and mangly hair where you body hasn't been recieving the right nutrients.
Eat healthy - plenty of fruit and veg. Drink plenty of water for the skin, and EXERCISE. Thats the main factor, I can't stress it enough. Exercise will help you in many ways than one.