How to Perform the Barbell Upright Row
The deltoid muscle group is made up of three heads: anterior, lateral, and posterior. Many athletes emphasize exercises targeting anterior or front deltoid-dominant which can lead to overdevelop front delts and underdeveloped lateral and posterior delts. No routine is complete without a shoulder exercise designed to hammer the lateral delts.
The barbell upright row is a stellar compound pull exercise used to target the lateral or side deltoid muscle. The anterior or front deltoid, supraspinatus (rotator cuff), brachialis (lower bicep), brachioradialis (upper-outer forearm), biceps brachii, middle and lower trapezius, infraspinatus (rotator cuff), inferior digitations of the serratus anterior (boxer's muscle), and teres minor (rotator cuff) act as supporting muscle groups during the exercise. 
Supporting muscle groups assist the target muscle group(s) during the movement. The upper trapezius and levator scapulae (rear neck) act as stabilizers during the movement.  Stabilizer muscles help maintain a posture or fixate a joint by contracting without significantly moving. 
Shoulders can be hit with a higher frequency and volume compared to other muscle groups because they're comprised of a higher percentage of slow twitch, endurance muscle fibers.
How to Perform the Barbell Upright Row
Begin by placing a barbell on the floor or rack pins and selecting the appropriate working weight. Ensure you add an even amount of weight to both sides of the bar. don't place 10lbs on one sides and 25lbs on the other side. Uneven loading won't improve your gains and will likely lead to an injury.
If this is your first time performing the exercise then pick a conservative weight that you can safely lift for 8 to 12 repetitions. As a reference point, the shorter Olympic barbell usually weighs about 30lbs and the longer barbell usually weighs about 45lbs. For many using only the bar is a great starting point.
Once you've selected the appropriate working weight approach the bar with a hip width stance. Pick up the bar from the ground or rack pins with a shoulder-width, or wider, pronated grip (palms facing away from you). Taking too narrow of a grip will cause excessive internal rotation of the shoulders which decreases the subacromial space (the area between the greater tubercle of the humerus and acromioclavicular joint) and may lead to supraspinatus tendon and the subacromial bursa impingement. 
You can use a traditional grip (thumb wrapped around the fingers), hook grip (fingers wrapped around the thumb), or a false grip (thumb and fingers on the same side of the bar.
After setting your stance and grip, take a deep breath, brace your abdominals for impact and stand tall with an upright posture, chest high and shoulders retracted. Keeping the bar close to your body, begin pulling your elbows up towards the ceiling.
Imagine there are two strings attached to your elbows from the ceiling, pulling your elbows directly upward. During this pulling it is okay if the wrists bend; ensure the elbows stay higher than the wrists throughout the entire movement. If you find yourself swinging your body, raising your shoulders towards your ears, or allowing the wrists to raise higher than your elbows then the weight is too heavy.
Continue lifting the barbell until you reach the desired height; for many, this will be in between the lower chest and collarbones. Hold the barbell at the desired height to contract lateral delts and hold for 1 to 5 seconds. Then slowly lower the weight in a controlled motion back to the starting position which for most is resting the barbell on or slightly off the hips. During the lowering portion of the lift ensure the bar stays close to your body, the elbows stay higher than the wrists, the chest remains high, and the shoulders remain retracted.
This exercise can be performed using straight sets, pre-exhaust sets, drop sets, rest-pause sets, supersets, tri-sets, giant sets, paused reps, partial reps, forced reps, or slow negatives. As with any exercise, the two most important components are high-quality form and progression.
Progression can take a variety of forms (e.g. more weight, sets, or reps, decreased rest period, improved rep quality, etc...) but strive to improve every time you walk into the gym.
Barbell Upright Row Form Tips
Watch the Grip Width - As previously mentioned, ensure you take a shoulder width or wider grip. Some may even find a snatch grip to be most comfortable when performing the barbell row. The risk of shoulder impingement and discomfort during barbell upright row dramatically increases when a narrow grip is taken.
Avoid Momentum - The barbell upright row provides maximum benefit when it's performed in a slow and controlled full range-of-motion. Check your ego at the door and don't attempt to upright row 135lbs.
Excessively heavyweights on this exercise will lead to body swinging in an effort to generate enough momentum to raise the bar. This momentum dramatically increases the likelihood of injury and minimizes the stimulus of the target muscles.
Hold at the Top - If you're looking to increase intensity then experiment with holding the barbell at the top position for 5 to 10 seconds. This will increase time under tension and the burn in the lateral delts. Increased time under tension is an excellent variable to adjust for progressive overload.
Strap Up - If your grip gives out before your shoulders and traps then don't be afraid to use straps. The focus of this exercise should be to work the lateral delts and appropriate supporting muscles. Popular strap options Versa Gripps, Valeo, and Spud Inc.
References"Barbell Upright Row." ExRx (Exercise Prescription) on the Internet. N.p., n.d. Web. 29 Oct. 2015.
"Kinesiology Glossary." ExRx (Exercise Prescription) on the Internet. N.p., n.d. Web. 29 Oct. 2015.