I've always done my shoulder press as full range when doing front press/military press, with hands shoulder width apart and pushing head forward when the bar passes it on the way up and pulling my head back so the bar just passes my nose on the way down.
When doing press behind head I only go to the bottom of my ears and pause before pressing the bar back up. Hand spacing on this move is wider than shoulder width so that your forearms are at right angles to the floor when in the lowest position.
D/Bs allow you to go full range as well, but I like to keep mine wide at the top of the move to keep the tension on the shoulders. I find letting them come in to touch at the top takes the tension off the shoulder and makes the move easier.
D/Bs are good for doing Arnold Press, neutral grip press,alternate press both seated or standing. Sometimes you can handle more weight when you do alternate press with D/Bs, as you can put all you effort into pushing just one D/B up at a time.
Just remember when pressing overhead, not to overload the bar or go too heavy with the D/Bs as it's very easy with this exercise to pull your back as you tend to twist when pressing.
God luck!
