Small changes can often have big results. Check out this article from Mens Fitness on how to take your core to the next level!
The serratus anterior muscle looks like fingers pointing from your ribs to your six-pack (raise your arms, and you may be able to see yours). It's vital for healthy shoulders and makes you look especially ripped. But most guys just aren't lean or muscular enough to reveal theirs. To boost yours, do 10 to 20 reps of any of the following moves before your regular workout.
Get on parallel bars as you would to do dips. Keeping a slight bend in your elbows, let your body sink down between your shoulders (it will look like you're shrugging) and then spread your shoulders and rise as much as you can. Your arms shouldn't move.
B) SCAP PUSHUP
Get into pushup position and lower your body between your shoulders without bending your elbows (you'll only move a few inches). Then spread your shoulders to come up. Be sure to keep your core braced throughout. It's the same idea as the dip shrug.
C) ONE-ARM SPLIT-STANCE CABLE PRESS
Attach a D-handle to a cable pulley and hold it at chest height. Get into a lunge position. Press the handle forward, keeping your shoulders square with your hips.