It doesn't matter if the tags are capitalized and tags are a way that people can find your post. My tips for using the tags would be to make sure that you use up all of them, even if you run out of things to tag. For example I sell crocheted items and I'll usually tag random items that would explain what I'm selling, how it's made, what it's made out of, and who it's made for. Think of the 5 w's haha, then if you run out of words and phrases to describe your item start tagging things that are popular. I've tagged the word jewelry before and I don't sell jewelry but if someone searches the word your post would come up and they may fall in love with what you're selling.
