Based on a post I saw here some time ago I have been having great results with the round carpet pads sold for furniture leg tips. They have great adhesive and are just the right size - I use the 1" and snip about 1/4" off for more flat surface at the corner. When I stick them on the shelf and riser I leave a gap for feather clearance. I then use a razorblade to trim the shelf side until I get the arrow flying to where I am looking.
For a long time I have used the Martin leather rests and, on my Bears, a bear style rug rest with leather riser pad (Three Rivers version).