

The best way to learn fiddle (non-classical violin, viola, or multi-string instrument) is to jump into a group! If you're not able to join a school group, here are some local options: Stillwater Music youth and adult groups, iAM MUSIC, Steezy Strings, and Irish fiddle sessions on Sunday afternoons at 11th Street Station.
Jazz method books include Jazz Fiddle Wizard and Jazz Fiddle Wizard Junior, Jazz Violin (by Matt Glaser and Stephane Grappelli), Modal Jazz Etudes for Violin and Viola: The Frame Method, Violin Mode Scales and Arpeggios: The Art of Improvisation, Enclosure Studies For Jazz Violin: A Complete Guide to The Art of Jazz Soloing With Diatonic & Chromatic Enclosures, and any number of fake books/real books.
Fiddle method books included The O'Connor Violin Method, Fiddle Tunes for the Violinist, Hot Licks for Bluegrass Fiddle, English, Welsh, Scottish and Irish Fiddle Tunes Songbook, The Complete Irish Fiddle Player, and The Fiddler's Fakebook.
Jazz & Fiddle

Solos for auditions/competitions
If you need some tunes for ASTA Certificate Advancement Program, university auditions, or fun, here are several arranged by ASTA level.
Level 1-2
Mark O’Connor: Violin Method Books 1, 2 (also for viola)
Dabczynski & Phillips: Basic Fiddlers Philharmonic Old-Time (or Celtic) Fiddle Tunes
Deborah Greenblatt: The Viola Fiddling Tune Book
Martin Norgaard: Jazz Viola Wizard Jr., Books 1, 2
Level 3-4
Edgar Gabriel: String Groove, Ideas for Improvising (also for viola)
Darol Anger: All Star Bluegrass Jam Along: For Fiddle
Dabczynski & Phillips: Fiddlers Philharmonic Encore for Viola
Ann Witt, Scottish Fiddling for Viola
Level 5-6
Jim Snidero: Easy Jazz Conception - Violin
Jack Wilkins: Essential Jazz Etudes: The Blues
Mark O’Connor: Limerock
Jean-Luc Ponty Collection
Level 8 and above
Mark O’Connor: The Fiddle Concerto
Curtis Stewart: 24 American Caprices
Edgar Gabriel: Theme and Variations for Solo Rock Viola