My newbie mistakes (again!):

1. too many LC products like Atkins muffins and bread (cause cravings for me)
2. not eating regularly every 4-6 hrs (I sometimes don't eat for 7-8 hrs and then will get so ravenous that I'll eat anything that's not nailed down)
3. not eating LC when eating out (so easy to 'cheat' and justify it being really good)

I'm sure there's more, but those are my big ones.