You don’t greet people. Say, “Good morning/afternoon/evening” and ask how people are doing, even when you’re just texting someone. Don’t be all business all the time. Take the extra second and be polite.  

You are totally unaware of your surroundings. You need to focus on more than just yourself. 

You shake hands when you’re sick. It’s polite to protect others from your germs.

You leave messes behind. Clean up after yourself.

You give one-word answers (or even worse, your default response is,“I don’t know”). You can just say that you don’t have an opinion. Take a little time to say more than “no”.

You exhibit negative body language. Talking to someone with your arms crossed conveys timidness or arrogance.

You constantly check your phone when you’re with someone. Unless you’re waiting on an important call, put your phone away.

You attack others on social media. Don’t put anything on that screen that you wouldn’t say about yourself.