Use Hashtags to connect your posts to popular ‘Categories’ within your social media. If you had a hard day at work, poured yourself a glass of wine and snapped a picture of your feet, the wineglass, and the fire you might post something like this: “My reward for a hard day’s work #wine #relax”
Hashtag Basics:
We recommend that you have a handful of hashtags that you use regularly and then a few other hashtags that are more specific to the video and relevant for current popular hashtag trends. Don't use a trendy/popular hashtag if you video is not related.
The recommended Quantity of Hashtags vary from network to network as do which hashtags are trendy or popular - so read up on the specific for each network and use the native hashtag tools for discovery:
Hashtags are not as powerful as they used to be since they dilute quickly because there is no quality control for relevance. Many people post unrelated content to what they think are popular hashtags regardless of relevance- algorithms exist to detect this based on the engagement (or lack thereof) of the first few viewers. In other words - don't try to trick the system.
Not only is it important to include hashtags in your posts, you also want to make sure that you are using them intelligently. It’s important to use hashtags that are popular and relevant to your brand. We recommend that you measure the popularity and performance of trending hashtags. There are many great tools available that help you find the best hashtags and also measure their trend over time. A few of these tools are: Hashtagify.me, Brand24, and Rite Tag.
References:
How to find Relevant Hashtags on Linkedin