Lol...what's with all the Indian curlbros here Ram, Anil, Ajay, Ramesh ? This won't make much sense but stop focusing on isolation to start out with. Do Squats, Deadlifts and close grip pullups (chinups ) and watch your biceps explode. If you have to ask for photos and more details on these basic exercises chances are you haven't been doing any actual lifting. Just curling biceps every other day wont get you big arms.
Disclaimer : I am Indian too but not being a curlbro has helped me get Hrithik Roshan sized biceps (if that makes sense)
The methods above are each valid and notable in providing a reasonably accurate range of the "true body composition" of the tested individual. However, each method does possess its own individual limitations, indeed precluding to the existence of so many variable methods available for an individual to use. Therefore, the actual method of testing body composition is not as important as the consistency of measurement in between each test. (See internal consistency for merits on testing in this manner.) If an individual is to be tested from one period to the next, all factors should ideally remain as similar as possible to reflect the best indicator of true change in composition.