My five life hacks:

1) Listen to people.
2) Remember to say please and thank you.
3) Write down a list of important phone numbers/addresses, and keep it in your wallet and/or in a desk or somewhere that isn't an electronic device.
4) Cook in bulk and freeze mealsize portions for later - but wait for the food to be completely cooled before you put it in the freezer!
5) Remember that everyone is worried or insecure about something, and most people are a little self-involved - so don't worry too much about what others think of you or the "bad impression" you may create by being less than perfect (read: human).