I usually browse through the forums of interest and open all interesting posts, until I get to the first that isn't bolded, since that one I've read before.
Most of the time I don't read posts/threads primarily to answer them, but to learn.
Poorly formatted (wall of text) or really poorly written posts, I often close without trying to decipher them. If the OP can't be bothered, neither can I.
I use the "New posts" link in the sidebar. With both the "Unread threads" and "Unanswered threads" filters saved as my defaults. Occasionally, I'll browse forums which interest me for unanswered threads.