I didn't answer about tags because I don't know of a guide.
I just found that if you search on tag [word that you think might be a good tag], you'll get lw articles with that tag, but that would be a process of exploration rather than knowing about common tags.
I found that it is possible to list all posts with a tag via a short URL, e.g. on parenting it is
http://lesswrong.com/tag/parenting/
But this doesn't show my postings with that tag. Can it be that only posts in Main are found by that? If so is there a different shortcut that will (also) lists hits in Comments?
This is a thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. The previous thread is at close to 500 comments.