I've been studying swing and gypsy jazz for a few years now (since I started violin seriously). I read music okay, and have reached what I'll call early intermediate level. Yet I still play about 90% in first position, only going to third position to reach high notes on the E string. I seem to have a problem reading in third, as I can't seem to associate the notes with the fingers, or as related to the notes in first. I can force myself very slowly to play tunes written just in third, but I can't develope any speed at it, let alone improvise. At my age, I will probably never bother with 2nd. or 4th or beyond, but I think third is rather mandatory in this style of music.
So of you better players out there, what materials helped you when you started learning third?
Violin's swing the best!