In The Practice of Practice, I recommend learning the tumbao and clave patterns on conga, or learning any rhythm instrument. Here’s a lesson on playing the guiro, from Bobby Sanabria. He teaches not only how to play it, but where the patterns go in the clave pattern.
Erin McKeown first opened my eyes about how practice can be very different depending on the kind of music you’re making. The kind of creative approach Erin uses to get better is covered in more detail in Chapters 26 and 38 of “The Practice of Practice,” available on Amazon. Below is a recording of my 2011 interview with Erin, talking about how she gets better.