Re: setteling into pins. stretching exercise help
I like to start by making certain that my shoulder is on the mat (while being pinned). This helps tori appreciate the need to get the shoulder down (otherwise escape/reversal is really pretty easy) as well as giving us both something besides the 'finishing' move to focus on and helps slow things down so the mechanics can be correct/corrected and the stretch can happen slowly.
Remember that these 'techniques' are really conditioning exersizes so the ending up pinned is really not the correct end state of the drill.