@iBud  I think you're doing right to concentrate on the bow rather than your arm.  There aren't many ways to keep the bow straight.  Your upper limb will be doing the right things as long as the bow stays straight.  Make sure you have enough flexibility in your fingers though.  There is a training device called the Bow Right that forces you to keep the bow straight.  Fiddlershop sells something similar to it.  You might try double stops while using that device, if you really want to keep everything in line and form some good habits fast.

Edit 10/01 09:13 EDT:   Of course you want to make full length strokes, using every inch of the bow, when you are training for straight bowing.