Something that worked for me was the eat the same thing every day... for two months. That way I only had to count calories once, and knew exactly what to buy and could prepare it mindlessly. Once I firmly decided: *this* is what I eat, it was so much easier to stick to it. In fact I'm thinking of going back to it.
5'0" female, 44 years old. Started Primal October 31, 2011, at a skinny fat 111.5 lbs. Low weight: 99.5 lb on a fast. Gained to 109 on sugar cheat. Reset with 85P / 90C / 90F. Currently weaning off fat to 85P / 90C / 60F.
MY PRIMAL: I (try to) follow by-the-book primal as advocated by Mark Sisson, except for whey powder and a bit of cream. I advocate a two-month strict adjustment for newbies. But everybody is different and other need to tweak Primal to their own needs.