Guidelines for Upvoting and Downvoting?

I’ve only recently joined the LessWrong community, and I’ve been having a blast reading through posts and making the occasional comment. So far, I’ve received a few karma points, and I’m pretty sure I’m more proud of them than of all the work I did in high school put together.

My question is simple, and aimed a little more towards the veterans of LessWrong:

What are the guidelines for upvoting and downvoting? What makes a comment good, and what makes one bad? Is there somewhere I can go to find this out (I’ve looked, but there doesn’t seem to be a guide on LessWrong already up. On the other hand, I lose my glasses while wearing them, so…)

Additionally, why do I sometimes see discussion posts with many comments but few upvotes, and others with many upvotes but few comments? If a post is worth commenting on, isn’t it worth upvoting? I feel as though my map is missing a few pages here.

Not only would having a clear discussion of this help me review the comments of others better, it would also help me understand what I’m being reinforced for on each of my comments, so I can alter my behaviors accordingly.

I want to help keep this a well-kept garden, but I’m struggling to figure out how to trim the hedges.