A simple tutorial for ukulele & guitar players:

• Staying in the same key and time signature (e.g. key of C and 4/4 time), you can play countless tunes using the same chord progression (e.g. I-vi-IV-V), and just changing the tempo. See this medley of songs played with the same 4-chord progression
• Just changing the time signature allows you to play numerous other tunes (e.g. 3/4 or waltz time).
• Doubling waltz time to 6/8 with emphasis on the 4th beat produces a Doo Wop strum, and another genre of music.

Some great examples in this video by the Axis of Awesome (caution – a little colorful language):

https://youtu.be/5pidokakU4I