Hashtags started out on Twitter as a way to search the site. If users tagged tweets with the hashtag #SummerSchool, and you wanted to search for everything with that keyword, you would enter #SummerSchool into the search bar on Twitter and those tweets would come up in the results (similar to SERPs on Google). Since the inception of the hashtag on Twitter, they have migrated to several other social media sites such as Facebook, Instagram and Pinterest. Each site has slightly different usages of the hashtag, however in general they work as search triggers.
Create your own unique hashtag for your related posts
You can take advantage of the hashtag system by creating a proprietary hashtag for your posts. The hashtag can be a made up acronym, or words put together that mean something to the searchers. If your followers know your hashtag, they can search for your posts and keep track of any that they may have missed or want to revisit.
Register your hashtag
In order to own your hashtag outright, you need to register it. You can register the tag at https://twubs.com/p/register-hashtag. Registering will authenticate your use of this particular hashtag and give you a claim on it for all future use.
Follow trends and participate in them
You can place your hashtag on other items related to your conversations, however do not overdo it. Your goal should be to encourage your followers to remember and use your hashtag, not try to usurp another person's feed. Usurping is just bad behavior.
Promote your hashtag
In order to get your followers to remember your hashtag, you need to promote it. Promotion can occur anywhere your business goes. You can place it on signage at events, on brochures and on your sales slips. With consistent promotion, customers will become followers of your tag.
Short and sweet
Simple, easy-to-remember hashtags work the best, and people won't tire out their fingers typing them in. Less is more, and less with impact is a lot more.
Hashtags are labels
Hoard your hashtags like gold; do not frivolously make dozens of hashtags. Use a precious few to label your conversations, and stick to those tags. Think of them as file folder labels. Where do you file that conversation?
Words, no spaces
Hashtags can be made up of more than one word, but combine the words with no spaces like above with #SummerSchool. Too many letters spoil the hashtag. Keep them short if possible.
Capitalize the first letter
To identify the words in the hashtag, capitalize the first letter of each word. In the example above, it should read #SummerSchool. Do not use numbers or symbols.
Know the platform
Each platform has slightly different rules of use for hashtags. Ensure that you are using them correctly by checking their help section.