Over at T Nation Todd Bumgardner goes over some points you might want to consider before starting heavy overhead presses.
Before you start shoulder pressing we need to assess a few things:
Excessive internal rotation at rest
Scapular anterior tilt
Scapular winging.
Shoulder Flexion Test
Scapular Wall Slide checking T-Spine Extension
Exercises to address shoulder problems
Glenohumeral joint (GH) Internal/External Rotation:
Sleeper stretch with lacrosse ball
Active pec mobilization with stick
Lat stretch with jump stretch band
No money drill (with or without bands)
Serratus Anterior ActivationForearm wall slide
5 count scap push-up
Push-up plus
Feet elevated push-ups
Mid and Lower Trap ActivationFloor blackburns
Band pull aparts (front, behind the neck and diagonal)
No money drill with band
Scapular wall slides
Overhead Press set-up cues
Air: Take a breath of air into your belly and lock it there.
Abs: “Lock” your rib cage by contracting your abs.
Ass: Tighten your glutes!
Lats: Raise your elbows to create a lat shelf and then squeeze.