Avoid snacking on carbs if possible. Potato chips and other salty snacks will not be easy to remove from your teeth. If you need to have a snack, choose some fruits or another healthy food. Clean your teeth immediately afterward if you can, or plan on spending more time flossing later.
If you are only going to brush twice a day, do it when you are first getting up and when you finally go to bed. Early morning brushing gets rid of morning breath and deals with anything that settled in during your sleep. Brushing at bedtime helps your plaque-fighting saliva out, since it is going to dry up overnight.