Have a theme for your mix. This theme can represent how you feel about the person you are giving the mix to, or the type of relationship you have with them. The theme could also be an entire genre of music the recipient likes, or is possibly not too familiar with. However, if you are making a mix for someone whom you have romantic feelings for, try not to be too obvious or serious with your choices, unless you know this person shares your feelings as well.
Expose the recipient of the mixtape to some new artists and music. There is nothing wrong with putting songs the listener is already familiar with on a mix, but if you want your mix to be listened to more than once, you will have to surprise the listener and pick some music they do not already own or have heard too often.
Be creative with your mix. A good mix does not have to be just a collection of songs, but can have small snippets of dialogue from favorite films, standup comedy, or interviews. Sneak a few surprises into the mix to keep the listener actively engaged.