Don't eat straight from the packet.
Have you noticed how easy it is to munch your way through an entire sharing bag/jar of crisps/chocolates/sweets etc when you eat straight from the container? How often do you take notice of the serving suggestion? It's usually quite small.
Portioning out the recommended amount of food from its packet is a quick and easy way of saving yourself calories here and there, plus you still get to enjoy your snack of choice.
The next time you're tempted to eat straight from the packet, stop for a moment, check the serving size and put that amount in a bowl to enjoy. Over time, you'll save yourself hundreds if not thousands of calories!