Norgaard, Martin - Getting Into Gypsy Jazz Violin - Book/Online Audio - Mel Bay Publications

While I have no real desire to get good at this genre specifically, I still found this book quite helpful as a starting point for advanced players looking to get better at improvising in any style! I've used the entire jazz fiddle wizard series now, including both junior books and regular jazz fiddle wizard, and imo this one is best if you already have a solid grasp on your scales and basic triads: if those are still a work in progress for you, I'd recommend starting with jazz fiddle wizard junior, regardless of age.

The backing tracks for this are also well done and very useful; I love that all the actual tunes and the more involved exercises are recorded at multiple tempos.