In a nutshell: Be nice and be polite to other users
This is a policy on how to treat other users.
Respect other users Edit
No user deserves to be treated with disrespect, no matter the situation. If you have a disagreement do not try to solve the issue with verbal insults or by using profanities. Things said on the internet can hurt someone in real-life. Also, making threats against someone online is illegal; you can be arrested, charged, and even sentenced to jail time. Think before you act. If you are harassing another user you will be blocked for a certain amount of time (determined by previous offences).
Solving user conflicts Edit
All user conflicts should be solved peacefully. It is better to come to a compromise than to keep arguing. If you cannot compromise then simply stop talking to that user until you can come up with a solution. If you feel that a user has made a personal attack on you, you may report it here and an administrator will deliver a verdict.
Edit and Revert wars Edit
If you are having an edit war with another user, contact the other user on the other user's talk page or the article's talk page and make an agreement to stop the war. Revert the page to its original state and refer to the style guide for a solution. If the style guide doesn't give a guideline for your disagreement, go back to the article's talk page and create a poll in which users can vote to decide which version is better. Whatever option has more votes by the end of a 3 hour period will be considered the better version. If you continue to argue and revert/change the edit you may be blocked.
If you feel you have been unjustly banned simply state your case on your talk page and let the community determine your situation. If you have been unfairly banned you may be unblocked. If you swear and curse at a user on your talk page the ban will stay in place, or it may be extended to a longer period of time.