i do heavy straight bar curls for 8 reps 6 reps 4 reps and go up in weight every set. then i'll do db curls and preacher curls in the 10 to 12 rep range. The thing that gives me gains is the BB curls while going up in weight every set. The next week i'll add the two and a halfs on the same weight i did for that set the prior week. progress progress progress. thats what helps me get gains