A big annoyance of mine is when your title is longer than the actual content you post. If you have, like, a one sentence thought, I don't think it warrants a new thread. Just find an existing thread to put it in.
Some people like to post a brand new thread for every little thought that enters their head. Try to contribute to the community and foster good discussion.
Err on the side of NOT posting a new thread. Find every opportunity to put your thoughts in an existing thread. If there is no place for it and you think it is meaningful and well developed THEN start a thread.
If you are referencing a tweet, a video, an article, or some other existing content, embed it or at least link to it in your post.