If someone is going out of their way to help you out like:
-Helping you move
-Dropping you off at the airport
-Planning you a party for an achievement etc.
Offer to buy them lunch or something.
Never take someone's time for granted.
1. If a friend is starting a business, offer support by buying their product full price. Avoid begging for a discount.
2. Always let them know when they are being cheated on.
No you are not 'protecting' them by keeping it a secret.
4. Spilling a friend's secret is a no-no. Once you enter snake territory, it is hard to work your way back.
5. Don't be all buddy buddy with their ex after a breakup.
7. Do not take more than you give. Otherwise you are a mooch.
8. If their parent, sibling or partner were taken too soon, help them get back on their feet.
10. If someone is clowning your friend, never participate. Either check the hater, change topic or exit interaction.