Stropping: what angle and motion am I supposed to use?
Motion: You strop with trail-leading strokes, meaning you are “pulling away from the cutting edge”. Edge-leading strokes will cut into your leather strop, and you will want to cry if you do. You can start at the heel or at the tip, although it may be easier to start at the heel for most people. Also, starting with the tip increased the chance of the tip of the knife cutting into the leather.
Angle: In terms of angles, you want to strop at the same angle at which you sharpened and polished at. It’s OK if your sharpening and stropping angles are not identical. Just do your best to keep them relatively the same. Being off by a few degrees may affect the absolute sharpness you can achieve, but will not damage the knife.