There's nothing wrong with making a good "Bro-Rep" setting at the end of a set until you feel your arms explode out of the pump. But at the beginning of a workout, one should be a little more purposeful and focus on the following:
- Controlled motion
- Full range of motion
- Core stability
- Time under tension
Try this complex for biceps, shoulders, and Triceps:
The magic is in tempo. Make each repetition at least 30 seconds. Start with two dumbbells and hold a dumbbell by your side while the other arm is working:
- Bicep curl to full contraction.
- Turn the dumbbell to a neutral shoulder press position.
- Shoulder press until full extension. 1
- Turn it back into a neutral handle.
- Perform a triceps extension to reach the full range of motion without change. Elbow position on the way up.
- Squeeze slowly on the shoulder.
- When you reach the rack position, turn your palm up to point the handle up.
- Make a slow, negative bicep curl.
- Repeat the process on the other side.
No challenge enough? Increase the weight. Now shake your arms for 20 to 30 seconds and make the entire set 6 more times 6 times.
Once you start accelerating or swinging, the weight is too heavy – save your reps for later. Remember, the slower you move and the more you tremble, the better!
Watch for one arm that fights more than the other. Until you've balanced it, use the weight your weaker arm can do and use that weaker arm to start the sets when you're the freshest.
Another variant you can do is to simultaneously execute both arms:  You must reduce the weight slightly if you are doing both arms.
The upper body exercise you are missing
A new large shoulder exercise