I know that's its a cliche, but get a teacher.
Somebody who actually makes their living playing arco, or at least has been trained to do so.
Part of the deal is looking/watching/thinking/practicing all of the moves, angles, concepts that one can absorb. For me, the most signficant pieces, though, are seeing and hearing an actual human make a gorgeous, fluid, powerful sound on the DB, seemingly effortlessly.
It always helped me to see somebody doing, from 5-6 feet away, what I was dreaming of being able to do. Real inspiration, there.
A teacher, too, can provide feedback about little, seemingly insignificant things that we are doing that will cripple our playing forever if left unfixed.
In my experience, there was nothing like sitting in the room with a pro orchestral player or an arco virtuoso soloist. I have been lucky enough to do so and it left an indelible mark on me. Hearing a great player, week after week gets the sound in one's ear and makes success seem attainable. It builds the hope that, maybe one day, we too can sound like that; that these sounds aren't made somewhere in bass heaven, but are produced by actual humans...
