Mixtapes can come in different forms–sometimes a mixtape is just a collection of one’s favorite tracks, sometimes it is a collection of tracks put out by a sinlge artist. Sometimes they have small edits made to them, like a DJ saying their catchphrase.
Try creating a mixtape of your own. Mixtape is broadly defined in this case. It can just be a collection of songs with some theme (genre, etc.), or you can mess with the tracks. You can add a small touch here and there or edit the tracks to your heart’s content, adding outside sounds using tools from your favorite audio editing software.
I’ve been playing around with Audacity, which is free, so that cold be a good place to start.