I'm Using A Book For References In Grading Though Question Old With New.

6th edition is fine, Photograde online from PCGS is also a great free reference, nothing better than hands on experience of looking at tens of thousands of coins with your own eyes. I go to auction viewing as often as possible, to get my hands on as many different series as possible, coin shows as well, I'm lucky enough to have Heritage Auctions only a few miles from my home.

I can't recommend the ANA Summer Seminars enough I've been through the grading courses at least 3 times, in total I've think I've attended 10 or 11 weeks over the years. Once the world get's back to a more normal era again, things will be easier when coin shows start up again.

The books are good but nothing will help better than a good mentor and lots and lots of hands on looking at coins. I also suggest the EAC grading guide for advanced study in early American copper coinage. Get comfortable with the circulated grades first then move into the difference in Mint State coins, study minting processes as well, this will help you to better understand things like strike characteristics, specific year and date issues, among other things that are just going to help you with the process better.

If you have some spending money, buy some really cheap slabs (graded coins) on ebay and use those for reference when grading your own coins. Nothing like having a coin in hand to use as reference. There's a lot of people like me who spent $35 for have a coin graded to only find out it's worth $1. I found that the photograde images don't do a great job when trying to grade between MS65 vs MS66 vs MS67 or 68. The difference is so minimal that it becomes spectacular...

I personally prefer PhotoGrade as a reference and I prefer the online color versions from PCGS and others over the book by Ruddy for circulated coinage (AG-AU). For uncirculated coins I prefer a book "How to Grade U.S. Coins" by James Halperin. This book shows each coins high points of wear to determine unc from a high grade AU and it offers color charts that show which areas of a particular coin are more serious than others when it comes to blemishes. For example: several small scuffs in the hair detail of a Morgan dollar are less noticeable than one on the cheek or in an empty field and therefore not a serious.