Composer and music professor Loretta K. Notareschi has written a set of etudes for Ukulele which has just been published by Disegni Music. Titled Five Etudes for Solo Ukulele, they are fingerstyle studies for the advanced beginner, and quite accessible if you’re interested in developing deeper skills on the uke. I did the final music engraving of the book, which has both notation and tablature.