I learned basic classical technique on violin after having had played guitar all my life. After that, I was self-taught (which I consider the best method).
I play all manner of celtic music, a bit of jazz and although I read fluently, I have learned several difficult Bach pieces BY EAR.
I decide on all my own bowings and shifts and it sounds like I want it to.
My main occupation and love though is Irish and Scottish jigs, reels, strathspeys, marches, airs, polkas, slip-jigs, slides, mazurkas, waltzes etc.