Hashtags help categorize a post to the theme of the overall message, creating an opportunity to find the post when other users click the hashtagged word.
The first rule of thumb is to avoid using overused hashtags. Words such as dog, fashion, blogger and dinner are too common. Instead, try specific hashtags such as #OklahomaDog or #TulsaBlogger.
You also don’t want to get too specific. Using #DinnerInTulsaWithMyBestie will not support audience growth since it’s unlikely that anyone else will use that hashtag. You want to find a good medium between common (but not overused) and specific (but not too rare).