i read your intro post above and i’m guessing that you should probably attack the thoracic spine and shoulders first.  Then your hips could be involved, as that could limit good rotation (bad rotation in golf is where your hips are frozen and you attempt rotation through the spine especially the lumbar spine which is bad and ultimately leads to injury) to get your arms high.  you probably should be working on posture in a big way, especially if you are typical young adult with bad posture and shoulders rolled inward.

in addition to the The Big Engine video recommended above, i would also watch the webinar on the shoulder: http://www.mobilitywod.com/livewebinars/the-athletic-shoulder-anatomy-physiology-function/

as for shoulder work, look at the internal rotation test as a guide, shown in this video:

http://www.mobilitywod.com/2012/11/its-not-just-absolute-position-its-stability-as-well/

http://www.mobilitywod.com/2010/11/episode-89-bro-your-internal–rotation-is-lacking/

some other videos: