I got this one and it is great for looking down through the glass at the coins: http://www.amazon.com/gp/product/B003EW1ZNC?psc=1&redirect=true&ref_=oh_aui_detailpage_o06_s00
Since you asked a rather specific question about grading and not photography, below are a few independent links, from varied sources, you may find helpful. http://www.icgcoin.com/news/grading-room/please-try-these-grading-tips-at-home/ http://www.coinweek.com/education/coin-grading/ron-drzewuckis-grading-coins-lights-loupes/ https://www.ngccoin.com/news/article/4404/ http://boards.collectors-society.com/ubbthreads.php?ubb=showflat&Number=2935424 http://www.coinworld.com/news/us-coins/2015/04/ngc-grading-room-confidential.html http://blog.littletoncoin.com/tips-from-the-pros-on-lights-for-coin-collecting/