I'm not the only mod (thankfully!), just the only one who posts publicly.

How to help? Thanks for asking! Here are the first three things that occur to me:

1. Sticking scrupulously to the site guidelines when commenting, even when it feels like nobody else is

2. Flagging comments that break the site guidelines

3. Emailing hn@ycombinator.com when there are particularly bad things going without moderation or particularly good things not getting discussed