Musicians commonly make mixtapes to promote themselves in between albums. Creating a mixtape takes time and preparation but once it's done there is still work to be done. Having a mixtape is great but if no one knows about it or hears it, its ultimate purpose is lost. If you have your mixtape ready to go, you'll need to pound the pavement to get the word out.
Make a list of small record stores that you can take your mixtape to for distribution. You should have determined whether you want to sell or give away your mixtape. Many small record stores will sell your mixtape on consignment if it is a good fit for the store. If you decide to give it away, pitch that idea to the store manager as well. Either way, you want to get your mixtape in the stores.
Take a few days to visit all of the record stores on your list. Take a copy of the mixtape with you to leave with the store manager. Discuss your distribution options before you leave the store. Make notes about how each store operates.
Wait a few days (no more than three) and make your rounds again. Visit all of the stores you have visited previously and follow up with the store manager.
Make a list of publications that you would like to get your mixtape featured in. Do a web search for publications that focus on the genre of music that you play. Many music publications have a submission process for music. Follow their process and send in your mixtape.
Pick out a song from the mixtape that you think will have the most widespread appeal, and offer it for free download from your own website or a site such as SoundCloud.
Follow up consistently. It may take some time before the media outlets feature your mixtape but you can get faster results from the record stores. Your main goal is to get your mixtape in front of as many people as possible.
In order to sell your mixtape legally, it must have all original music.
If you sampled anyone else's music, you must get all of the proper clearances before attempting to sell your mixtape.