What does not need to be said?

There are few things that should be known to and etiquettes that should be possessed by everyone. They are:

1. Whenever a person lends you something in your need and you say that you'll return it at a specified time (say, tomorrow) then return it on that specified time (tomorrow).
   

2. Whenever someone helps you in your financial distress, even with a small sum like ₹100, then do not make them look desperate every time they ask it back. It is their money and they helped you when no one did. Feel indebted to them because you are, literally.
   

3. When you take something from someone to use, take responsibility of it and return it in the same state as it was in, when borrowed. If something happens with it accidentally, feel obligated to pay for the loss without even asking.
   

4. When you give a particular time (say, 6pm) to someone to meet, then reach on time (on or before 6pm). In case of some unavoidable delays, be courteous enough to inform them beforehand. You may not value your time but there are people who do.

If I wrap up all the above points in a single sentence, then I'd just say that learn to value your words. Do whatever you say and say only what you can do. It develops a respect for you, within yourself and others.