I always start my day making boxes
A box for breakfast, lunch and a snack and take them with me wherever I go.
I have a big binder with pages that I write in what I plan to eat and just have to put in the time that I eat it. I try to space out my meals like the zone diet suggests:
3-4 hours for a main meal
2 hours for a snack
9 breakfast
1 snack
3 lunch
7 dinner
snack 1/2 hour before bed...