If you are someone who trains with weights on a regular basis and find that your arms are lagging behind your general increase in lean body mass then you should try something new. If you want to gain size on your arms you need to understand a few things about training arms.
The first is that your increase in weight should NEVER be sacrificed for form so you always need to make sure that your form is correct. The second is getting the "pump" in your arms which you get by super-setting both biceps and triceps.
The arm routine listed below in order to gain size in your arm is by training your arms three times a week. You should never do this routine permanently but if you want to gain an inch on your arms within just one month then you are going to have to dedicate more time to your arm training.
The arm workout will change from light weight for 15 reps to a heavy weight for 5 reps but it is all done on different days. The results of gaining an inch on your arms in a month assumes that you are eating correctly and getting at least 8 hours of sleep a night.
You should train this with high intensity and never rest more than 90 seconds between sets. This arm routine should be done at the end of your normal workout when you have worked on your other major body-parts. The following movements should be done consecutively without stopping or resting.
Standing Dumbbell Curls 5 sets of 12 to 15 reps and then super-set with
Seated Dumbbell Triceps Extension for 5 sets 12 to 15 reps
Standing Barbell Curls for 5 sets of 5 to 8 reps
Lying EZ Bar Triceps Extension (Skull-crushers) 5 sets 6 to 8 reps
Preacher D/B or Barbell Curls for 3 sets of 8 to 12 reps
Overhead Pulley Triceps Extension for 3 sets 8 to 12 reps