I don't know specifics for left to right vs. right to left, but I would suggest placing a tee dead center six o'clock, and sticking one at 3 o'clock on a left to right putt on the practice green.  Practice hitting this shot from various distances, and visualize where the putt will drop. 

I had problems holing side door putts until I learned of this drill.  It helped me tremendously for putts breaking both ways.

I would say take a few practice strokes halfway between your ball and the hole as if you were to putt it from halfway. Pick out a line from halfway and go back the ball and try to putt it on that same line. This should also help with getting the speed right too which in theory will get the ball rolling on the right line. I have the same problem though, i seem to miss more putts that are left to right, almost always because ill push it and miss on the low side. Confidence never hurts either.

Try spending time on the putting green.    A 6 footer to start,    Place a tee in the ground at the break.  That's usually about half way about 3-4 feet for a gradual breaking l to r putt.    Putt around the tee.   Keep moving the tee each time to adjust it to the point of the break when the putt is holed. .  Your final putts should break just left of the guide tee and in the hole.   After a dozen or so, remove the tee.  Practice  at different distances going around a the tee as a guide point.    Works for me.

I like it!  I used this for big down hill putts that break too.  Find the sweet spot and practice hitting it.  Pull the tee out and you can still drain em.  It's a good visual.

Hi Keith.

Try finding your line from the other side of the hole.