All the advice I have to offer, like others have said before me, is to pick something you feel committed to and make sure you stick to it. Personally, meal replacements never worked for me. I found that I handled things alot better being able to choose between healthy ingredients and cooking to my own taste (and in small portions ^_~).
The best advice, take it one day at a time. Some days you'll just breeze through, and other days you'll be standing in the kitchen fighting the urge to grab something bad.
If you live with other people it's important for you to try and mould your eating habits to your diet and to not let those around you have a negative effect on it. I still live at home and I have to deal with a lot of tempting food lying around in the kitchen (God, I'd love to live on my own). If that's the case, carry a bottle of water around with you and if you feel like grabbing something naughty, start drinking!