As a new member of this forum, I was just wondering if there are any "etiquette rules" that the people here abide by--obviously I know there are written rules, but what are some of the unwritten rules of using this site?

One question I have in particular is regarding old threads. I know that on some other forums, it's generally frowned upon to reply to threads that haven't seen activity in a long time, and was wondering if the same applies here. Often I will come across a thread that is several years old, and either I find the conversation interesting or have a strongly related question, and I will feel the urge to reply, but I hesitate to do so because I don't want to reply to old threads if that's not considered acceptable here. In those cases should I respond to the old thread? Make a new post with the same topic? Forget about it and move on?

Any other tips on how to interact on this site are greatly appreciated!