You'd be hard-pressed to find someone that doesn't want a better set of guns these days. And the good news? There's a correlation between aesthetics and strength. So increasing one will help the other.
Here's what to do:
1. Barbell Curl Isometric Hold Against Pins
You can do these with the pins at various heights. Curl the bar to the pins and hold for a four-second count, curling the barbell as hard as you can into the immoveable pins.
There's a fair amount of research to support positive training effects of isometrics in terms of improving neuromuscular efficiency and maximal force that a muscle can generate. Plus, you can use isometrics to ramp up the sympathetic nervous system prior to training and utilize post-potentiation activation.
2. Close-Grip Chest-to-Bar Chin
The chin-up has always been an effective arm-builder, but the chest-to-bar variant adds a new level of difficulty. You'll be surprised how much tougher this makes the chin-up. Adding additional weight usually isn't needed in most cases. The extra range of motion requires the biceps to contract further, relying less on the lats compared to a traditional pull-up.
3. Fat Bar Reverse Curl
Increasing the thickness of the implement you're using will kill two birds with one stone (grip strength and arm size). And there's a strong correlation between grip strength and total body strength.
An easy way to add grip work is by using a fat bar or adding Fat Gripz attachments to a standard bar. By simply increasing the demand of the forearms, you'll increase the number of motor units activated.
4. Close-Grip Supinated Lat Pulldown
It's a staple hypertrophy exercise similar in execution to the close-grip chin-up, but now we have the ability to add more volume and illicit higher levels of metabolic stress.
5. Seated Incline Dumbbell Curl
This was a favorite of strength coach Charles Poliquin because of the massive stretch it puts on the biceps through the whole range of motion. In Charles's words: "This exercise has the advantage of shifting overload to the brachioradialis and biceps brachialis at the expense of the biceps brachii."
Not sure what that means? Just try it and you'll probably feel what he was saying.