YWS is an international site, meaning there are many different people, from many different countries. It is important to remember that our languages may vary. For an example, I'm from Canada. In Canada we spell 'color' as 'colour', 'flavor' as 'flavour', and things such as 'spelled' can be spelt 'spelt' instead. This is also the case in Australia, and Briton I believe.
So when correcting grammar and spelling, keep those things in mind. I bet you wouldn't like someone telling you that 'color' wasn't the proper spelling, if you were from America, and so on.
Another thing to remember is that English is not always peoples first or second language. People come to YWS to practice writing in English. So don't get to annoyed if someone uses 'for' instead of 'to', they're learning, and it's your job to help them learn in a polite and friendly manner. We're all here to learn.
When it comes to different cultures and beliefs, people tend to get rubbed the wrong way. Common arguments are gay rights, and abortion. People have the right to their own opinion, no matter what ( unless they think it's a good idea to kill someone for fun ). Even when something's so terrible wrong to you, you have to remember that there's nothing you can do to change they're mind.
Strong opinions on such matters are usually passed down from family members, or are just a factor of how they were brought up.
If you are easily maddened by such subjects, my advice to you is to stay out of it. Those types of arguments go nowhere, and they only create conflict between people that could, and are, your friends.
If you do get involved in an argument, always respect the other peoples opinions. Because after all, they're only opinions.