The Suzuki Method is more than just "learning by ear." The method emphasizes the importance of immersion in a community of musicians who share your repertoire and absorb lessons from one another in the pursuit of serious musical study.
Not all aspects of the method are easily applicable to the uke and much of the method was developed specifically with a young child in mind. The uke lacks dynastic, formal schools of technique, so many aspects of the Suzuki method (developed to teach classical instruments with more illustrious histories than our humble ukulele has) are more abstract in application and the method's rewards are more limited on ukulele. This is a bit of a shame; the ukulele's demure size requires little modification for children to play it well, and I'm sure its music box-like sound would inspire many children.
Here is how I have applied what I've learned through the Suzuki method to ukulele:
Listening exercises:
-Listen daily to performances of the pieces I'm learning (Jake Shimabukuro's "Departure Suite", a collection of American folk music, and Howard Heitmeyer's arrangement of "Here, There, and Everywhere").
-Listen daily to great ukulelists (right now, that's Lyle Ritz and Derick Sebastian).
-Keep a journal in which I critique and reflect upon these performances.
Involvement in the ukulele community:
-***Read this forum!***
-Attend ukulele picking circles whenever possible.
-Attend concerts that feature good ukulele playing or songs from the repertoire I intend to learn to play on the ukulele.
Daily practice sessions:
-Make a sound, listen to it as it decays, assess its tonality then reflect upon how I might improve it. Rinse and repeat.
-Practice simple exercises while focusing on elements of sound. For instance, if I am practicing scales, I listen for pitch, dynamic level, and tonal color and practice as slowly as necessary to ensure evenness across all three.
-Improvise a melodic idea. Repeat that idea. Develop that idea. I do this both on one string and on three strings in both open and closed positions. I then transpose these "solos" to other keys.
-Spend time refining and expanding my repertoire every day
-Consider the mechanics of playing ukulele and strive for a solid technique (this is difficult due to the paucity of classical ukulele instruction) that enables me to more readily control the sounds I make. I am making some progress in this area by adapting classical and flamenco guitar technique, but the ukulele is not a guitar, and my progress has been limited by the paucity of dynastic ukulele instruction.
That's not everything, but in summary, I suppose I have adapted the more structural elements of the Suzuki method to ukulele.
Ukettante, thank you for posting this thread. While writing my reply, I reflected upon the ukulele's status as an approachable instrument and wrote an essay that I'll post another day in a thread of my own. Had I not read your post, I almost certainly would not have stepped back and considered how my childhood instruction has influenced my approach to learning ukulele.