Instead of placing your right hand on the cantle and pulling it toward you as
you pull yourself up, try placing it flat on the far side of the saddle just
behind the stirrup bars. As you press your hand down it will give you
leverage to pull yourself up, plus the downward pressure on the offside will
help keep the saddle from sliding.
Of course, this assumes you are tall enough (or horse short enough) that you
can reach the far side of the saddle!
Linda Romander
San Francisco, Calif.