When I first began to workout a couple years back, i found that i also had this problem. What helped me overcome this problem was trying to make sure each arm completed the same amt of reps and same weight. Also when working out try to include some equiptment that forces you to use both arms at the same time like bench pressing...preacher curls. After about 2 months of so it seemed to have balanced out.
When i used the bench to workout my chest, i would find that i was getting the right side up quicker than my left, but i just focused on completing reps evenly with both arms.
hope this helps