More reps with lighter weights shall do the trick.

Also, you have to trick your muscles. Change up the routine every so often. Instead of resting 30 seconds between sets, rest 45, then rest 10.

You will be shocking your muscles and they won't get used to what you are doing.

I agree, more reps with lighter weights. I will do 30 reps of 12 sets for each arm (curls) with little 12 pound weights for definition. But I am a guy, so you will need smaller weights.

Well, I'm going to tell you to do just the opposite of the last two replies Jigga. Increase your weight and perform fewer reps. Hypertrophy (muscle mass) is attained via time under tension (weights) and diet. Diet is all important here. Do some research. Look for programs that are hypertrophy specific.

thanx guys

Everyone is right to a degree. You want to lift heavy for strength benefits and fast twitch fibers and you want to "rep out" for slow twitch. You want to change your workouts about every six weeks or so to use different exercises or a different positive or negative movement. Women usually dont consume enough protein and make sure your carbs are complex and not to late in the day. Carbs are for energy and at the end of the day we slow down and dont use up as many calories.

Yeah I agree with linpd - heavier weights lower reps - say 9-12.