To promote your work and hopefully increase sales, you should go to where your audience is. This seems like a no-brainer, but it does get complicated. For example, you may be happy posting to instagram where your friends are. However, your audience may be on Facebook where you are not even posting. Thus, take a moment to think about who your audience is - it Amy be that some are in one platform and other in a different one. That's OK, just make sure to promote your work to both.