this is what I did...take a picture of yourself in you bra and pants , stick one on your fridge, one inside your fridge, some on your cupboards, some inside your cupboards, and most importantly one in your purse so when you are tempted to go buy all the forbiden foods , you get a sharp remiinder..... also set small and reasonable monthly targets, reward yourself with treats which are non food related so as you don't associate food with rewards, some ideas are, a new haircut, manicure, new lipstick, get your eyebrows done, new handbag, new shoes, new perfume, a silk scarf, jewellry and as the weight drops off, new clothes....
...most importantly don't loose weight because your parents or other people are telling you to, do it for yourself!... and if you do have a bad day and binge on the naughty foods, don't despair and say "oh well, I've blown it now, I might as well carry on scoffinig tomorrow"...just accept you had one of those days, and go back to being an angel for the rest of the week...after all a little bit of what you fancy does you good, you are not on a diet , you are re-adjusting your eating habbits of a lifetime....
...I hated the idea of exercising in public, so I bought an exercise bike, and instead of sitting watching my soaps on the sofa, I'd sit on the bike and watch my soaps (1.5 hrs a night!!)...the weight will drop off quicker, your fitness will improve , so I didnt feel so selfconcious about joining the gym when I felt the time was right....the staff in your local gym will be fantastic, so dont worry , they will probably have ladies only night if you still feel slightly selfconcious.....
...goodluck, and if you are struggling, just pop on here , I'm sure there will be loads of Abers who will help you if your having a bad day....