Bodybuilders: Best way to build upper body muscle?

I'm a super tall skinny 19yr old guy around 155lbs, I have like zero body fat so building muscle isn't too difficult for me. Well I just started a job recently where I do a lot of demo work (Taking apart houses down to the frame, very physical). My arms have gotten bigger as well as my abs getting more tone, and my legs have always been in good muscular shape.

My problem is upper body, specifically pecks and shoulders. I want to build mass there but so far no luck. When I go to the gym, I take a bottle of water with me that has powdered creatine diluted into it and drink I it throughout the workout.

My schedule is flexible enough to work around any kind of workout routine, so I would like any input on the best way for me to build up some muscle mass in my chest and shoulders! Any advice from diet, to workout routine, even to sleep schedule would be welcome.

Thanks!
Bodybuilders: Best way to build upper body muscle?
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