We often tell new folks to #Mastodon to follow #Hashtags, but we never tell people how to do it or which ones to follow. To follow a hashtag from the web client (it varies on the apps), click on the hashtag, and then click on the person icon with a +. Once you have done that, the icon changes to a person with an x; clicking on the x icon will also unfollow the hashtag (see my before and after screenshots). You can see which hashtags you follow by accessing the menu next to your profile name.
