Your biceps are only going to get so big before you have to gain more overall mass. They become involved during most exercises for the back, and since they're already a relatively small muscle group, they need little direct work. Keep your direct biceps work to 4-5 sets. Some people can get by with more, but it's usually not necessary. This is a good example of less being more.
You have to really watch it when you're directly training the upper arms. Like I said, biceps are heavily involved in most back movements, while triceps become heavily involved during chest and shoulder training (any pressing movement involves the triceps). Less is more my friend.
Here's a biceps routine that I do at the end of my back routine:
Barbell or Curl Bar Curls 2 x 6-8
** Concentrate on good form; at the top of the curl, contract the biceps by squeezing them - this makes you maintain a conscious effort to keep constant tension on the muscles. 2-3 second negatives.
Incline DB Curls 1-2 x 6-8 or 8-10
** Start with the dumbbells held at your sides while seated on a bench at an incline. Start with your palms facing each other. Curl each arm at the same time while supinating the wrist as much as possible towards the top of the curl (meaning, rotate the wrist so that the pinky finger is higher than the thumb at the top). Give the biceps a good squeeze and then lower for 2-3 second negatives.
Chins (palms facing you) 1 x to positive failure
** When you curl yourself upward, don't sell yourself short; curl yourself upwards as high as you can go, until you can't go any higher. Lower yourself slowly until your arms are fully extended, 2-3 second negatives.
After each set for biceps, flex them hard for about 10 second or so (I like to stretch them for like 1-2 seconds before flexing). You can also supinate and pronate the wrist a few times, which makes some sense to do since the functions of the biceps include curling the arm and aiding in wrist supination. After you're completely done with biceps training, do a few series of flexes and stretches (10-20 seconds each) finishing with good stretching.