Melissamarie, I know what you mean--try, try again!
The thing that has helped me is to have a plan to follow, rather than just something like "I'll eat better today." I don't mean it has to be every single meal and snack down to the crumb--although it could be!--but it helps me to know what my meal selections are, my snack selections, and so on, so that I can make sure I have the right foods in the house (and none of the "bad" foods!!). I also track calories in and calories burned using the FitDay tracker on the computer. That way I don't have to guess.
I was horrified when I found out just how many calories something like a fast food hamburger actually has! I mean, 900 calories?
I'm eating around 1200-1300, so something like that leaves me NO room!
Anyway, I'm rambling--good luck to you! Let us know what you're doing and if you have questions, etc.