This post may look odd as it has a picture of comments, but I want to make my point that people should vote on comments, especially those on their own posts. You can see that I do this in most cases. It encourages people to make comments as they can earn from them and it helps their reputation. I just seem to be seeing less votes on comments I make these days. In some cases I made a couple of dollars from a comment when the Steem price was a lot higher. Newer users will appreciate a few cents here and there. I'm over 1400 SP now, but that's not enough to give them much. That won't stop me voting.
Be aware that if comments deeper in a thread get voted on then it benefits the earlier comments. I learned this from a post on Steem.io. Of course you can only go down six levels.
Really good comments may earn an extra reward from me. Someone on Tsu called this 'comment cents'.