Here's a great infographic from SocialCaffeine.com about Twitter hashtags. I've posted a lot about them here in the past, and this graphic reinforces that info.
Pay attention to the bottom right hand corner - the Where To Find Popular Hashtag section. It has some great suggestions about where to find find the right hashtags for your content (remember that what you post doesn't always have to use #musicians, #music, #studio, etc.).