The best snacking advice I can give is to buy produce such as carrots, celery, etc and get some snack size ziploc bags. Wash and cut up the produce and put it in the bags, stick them in the fridge and whenever you need a healthy snack there they are.
The best thing I was ever told was to think of my calories as a budget. Know how many you can have each day and before you eat something ask yourself if you can afford it. If it's worth the amount you have to spend and you have the calories eat it if not rethink it.