Creating softball-sized biceps is part science and part art. The science factors in when considering the best exercises, their order, the number of sets, how much weight you should use, optimal rest periods, and even frequency. Fortunately, there's enough research to create some general guidelines on how to construct your workouts.
The "art" portion, on the other hand, comes only with experience and years of in-the-trenches trial and error. That means finding what works and creating your own customizations that make a movement more effective. If you're a beginner, you can't compensate for a dearth of know-how, but you can easily do what I've always done: keep an open mind and listen to folks who've been around a lot longer than me.
Here are three insider tips I've found to be especially effective for arm building over my 18 years of training.1. Don't Grab the Middle of the Dumbbell
You probably don't give much thought to how you grip a dumbbell when training biceps—in fact, few trainers do—but my preference is to go off center so that my little finger is pushed up against the inside of the dumbbell.
As I curl the weight upward, I find this hand position helps accentuate the tension on the biceps by greatly reducing the tendency to pronate my hand, meaning I'm less likely to turn my hand down. Hence, I can focus more on just lifting the dumbbell rather than trying to control its direction.
To work my biceps to their fullest, I supinate my wrists as far as I can, meaning I turn my hands up and then some, when doing dumbbell curls.
You may not think a simple turn of the wrist would have much to contribute to a curl. After all, the biceps are an elbow-flexor muscle, right? Yes, but they also help to supinate the wrist. So by the time I reach the peak-contracted position, I flex the biceps as hard as I can while also supinating. Without that extra twist, I find I'm unable to generate nearly as much tension and isolation in the muscle.3. With a Barbell, Focus on Pushing with the Pinkie Side of Your Hands
If you don't think the supination technique I just described can be used with a barbell or EZ-bar, you're mistaken. When I'm using a fixed barbell to curl, I focus on pushing harder against the bar with the pinkie side of my palms rather than the thumb side.
This simple change accentuates the stress on the inner portion of the hands when using an underhand grip on a bar. I've noticed it resembles the feeling I experience when I externally rotate my wrists doing dumbbell curls, and when you're as focused on the mind-muscle connection as I am, that feeling is everything.
One important trick I employ to improve each of these tips is to visualize my biceps working, not unlike how Arnold imagined his biceps filling up with each rep. Before I train arms, I'm already thinking about deliberately maximizing tension and blood flow to the localized areas.
When I first started employing these techniques to enhance my biceps development, I reduced the poundages so I could focus on the form and tension. Since then, I've been able to increase the loads without sacrificing form as the techniques have become second nature. I'd encourage anybody looking to implement these tips to follow the same route.