Commenting on posts is really one of the best ways to earn more using Steemit. When starting out, there isn't much of an audience for original posts. So until you gain a following, your best bet is to comment on posts that already exist and hope that the people reading it agree with what you say. It's win-win because by commenting on an already existing post, you gain notoriety, and their post gains value. At the end of the day, everyone wins!