It is actually the triceps that make up 2/3 of the muscle mass in your upper arms, so for bigger arms in general you should aim for a training ratio which puts more focus upon developing your triceps than the other way round. Nevertheless, your biceps cannot be ignored - so when you hit them, these 3 tips will help you hit them harder than ever!
1. Get Your Angles Right!
Train from all angles. Think about all the different positions your arm can be in while you carry out the action of flexing your bicep - you should try to incorporate as many of these positions as possible into your exercises. For example you could do 4 sets on the cable curls, 2 sets close grip then 2 sets wide grip. Maybe 3 sets of preacher curls with a neutral grip, hammer curls with the dumb bells (palms facing inwards) or regular bicep curls with dumb bells (palms facing upwards); I would only use 2 or 3 of those exercises per workout, not all at once. Use your imagination and hit those biceps from as many different angles as possible!
It is important to make sure you are keeping your body guessing, and that means hitting different set and rep ranges and at different intensities; you can start with warm up sets. For every exercise grab the light weights first and just get pumping, 15-20 reps getting blood to the arms - prepare your body properly! To vary your reps you can do it in so many ways, from the standard 3 sets of 10 or 3 sets of 8 it is time to evolve. You may decide to do a set of 12, then a set of 8-10 with heavier weight, then a set of 6-8 even heavier. If you are really going for size you could do 3 sets (8 reps, 7 reps, 6 reps) or at the other end of the scale you could 3 sets working to failure (obviously your maximum will decrease each time). Preacher curl is a great exercise for including 'negative reps' by which you lift the weight at regular pace but release as slowly as possible on the downwards phase. A real killer for this could be 3 sets of 8 (normal reps) +3 (negative reps - releasing for 10 secs each time).
3. Little and Large
Growth Hormone. Please bear in mind that this doesn't just pertain to training your biceps, it applies for other areas too! It is vital to remember that the release of this hormone encourages our muscles to grow to the extent that they do - so as common sense would have it, the more growth hormone you can produce during your work outs, the more you can expect to grow! So if you are training biceps alone for a whole session, we immediately have a problem. As established earlier the biceps only make up a third of the upper arm, so you can imagine how small the muscle group really is in relation to the rest of the body. This is part of the thinking behind training in 'splits' - by pairing up large muscle groups with smaller muscle groups (eg. Monday - Back and Triceps, Wednesday - Chest and Biceps, Friday - Shoulders and Legs) you can train them together and ensure that you are producing greater levels of growth hormone during your workouts.
Ensure you are working a larger muscle group in the same session as your biceps!