My biggest mistake, when I first joined Twitter was to follow lots of people indiscriminately. I've spent a lot of time un-following people since then. If you follow too many people, who don't share your interests, it becomes pointless because most of the content you see is irrelevant to you.

Useful tips there, I've linked to this post from a thread in your favorite business forum, for a member looking for tips to optimize RSS feeds on her writers' blog.