I thought of my pitches like golf shots. Imagine the ideal path of the ball. I threw mainly a sinker from the sidearm slot so I pictured it coming in a diving right under the righty's bat to his back leg. Lefties I worked inside mostly, so I pictured it starting just at his front thigh and coming right back to the inner half.
I always had a timing cue in my head. If I had guys on base I had a number in my head that I counted to after coming set and changed it each time vary my looks. I constantly thought to myself "stay back" as a way to avoid rushing to the plate.
Last thing, if my gut didn't like what the catcher threw down, but I still nodded yes, I tried to step off for a new sign. This was a constant mental battle, but I learned the hard way that a pitch thrown without conviction is a pitch that gets hammered.
Besides all that not much. Only a few thoughts are needed.