i have also found recently and in the past that it helps to make small changes at a time that you can live with, if that makes sense, often in the past when i have started new "programs" i've been fine for a couple of weeks to months but often the huge sweeping changes are too hard to stick to long term.
Also, as i think Mandie has said somewhere else on this site, allowing yourself a small treat every so often is helpful i think coz then you don't feel like having a huge treat coz you've already satisfied that urge....does that make sense???
and finally as has already been said, getting rid of any of the not so healthy food from your house removes the temptation to jsut go and eat it, much harder if you have to leave the house and buy something unhealthy to eat, but make sure you have healthy stuff in the house to eat instead, otherwise you might end up going out to buy crap anyways
sorry that was a bit long but the ideas just kept coming