Getting them lean and trim requires reducing your body fat percentage. If you want to give the individual muscles a little more shape and appearance of "separation" try ATV: Arm & Tricep Vanity. It gets the triceps, biceps, and shoulders and all that good stuff.
My body fat % is just shy of 18% at the moment. I don't know if I want to get it much lower.
Just do push-ups and pull-ups.
I had it check last week. 17.8%
If you have some medical issue,before starting any exercise routine consult your doctor. and only when u get a green signal u should proceed