Be careful in using hashtags; they might harm your post rather than do you good.
The most common error that people do when including hashtags is putting too many into a post that has too little text. The second? Exceeding the allowed number of hashtags in a single post. Social media accounts have policies on the proper use of hashtags. Take the time to know and understand them to avoid the crime called over hashtagging.
The general rule for using hashtags includes the use of the number sign or the pound sign before a word or a phrase without any spaces. Other than alphabetical characters, numerical values can also be included in a hashtag except for numerical symbols such as %, $, etc.
Unlike Twitter and Instagram, Facebook’s policy on who can see your hashtagged post would depend on what people share with you. Facebook does not automatically show posts with a given hashtag, you have to search for the hashtag on the search bar to see other posts. This means that even though your post is in public if you are not connected to your audience, they will not be able to see your post. Only people who follow your page or connected to someone who shares your post will automatically see your hashtagged post.
Though Twitter allows as many hashtags that can fit into 140 characters in a single tweet, they only recommend using two hashtags per post to maximise the content of the post. For Instagram, you are allowed to use up to 30 hashtags on the post itself or the comments section of a post. Though LinkedIn doesn’t have a set number of allowed hashtags per post, it is recommended to have 3-5 hashtags so that you don’t clutter your post especially when you have less text.
Unlike other social media pages, LinkedIn does not set a limit to the number of hashtags used per article. You can add as many hashtags as you like in your summary, headings and blogs but you cannot edit these hashtags once you have published your articles. With regards to Google+, the system itself provides related tags to your post therefore even if you do not include hashtags; you will still surely be found by those who search for your topic.