Let me say, I'm a full fledge collector first of many things and the seller in me comes second. It really bothers me to part with something I've worked so hard to acquire/find. Coins that I have collected, I buy so knowing that someday, they will eventually need be resold. Whether by me, my wife or children.......who knows? So......when buying a coin, I like the idea someone else won't mind owning as much as I have. So for this reason all my coins must have complete detailed strikes, minimal marks away from the focal areas, plenty of luster and perhaps some intriguing toning.
Over the years I have used a number of grading systems by noting the qualities a coin may have. Early on, I have used a Q1 thru Q4 notation, Q standing for Quality and whether a coin had 1, 2, 3 or 4 qualities about it. Another, I have used is an S for Strike, C for the Condition, L for luster and T for toning if it was special. I also may have added a Y for Yes or a N for No on the steps. Each of these four components must meet a gratifying level of eye appeal within the grading standards. So when viewing a coin, any combination of those letters may be noted for a coin and whether the steps were acceptable. A SCLTY coin will have it all. A CLTY without the S will indicate the coin is not fully struck or not all details are present on the coin but the condition, luster and toning are at a satisfying level and an added Y for yes indicates, there are 5 full steps. A SLN because the C and T are omitted, will indicate the condition is low, a MS63 or MS64 grade type coin and the toning is not all that special but has a nice strike and luster but the steps are not acceptable. Do not be alarmed when you see that there are very few coins noted with all four qualities, the reason being, they are rare finds, seldom seen and not always available. Outstanding toning is the major culprit for this as most high grade coins are lustrous without any toning. From personal experience, many collectors will dip rinse a coin that has scant or ugly toning to get a higher grade. This action, IMO, ruins the originality of the coin. The luster is damaged to a degree and over time, a coin will retone, get dipped again further destroying the coin's lustrous eye appeal.
Also keep in mind, not all dates can be easily located with perfect mark free or bridgeless steps. So I'm lenient in calling what has full steps especially on the tougher dates because I consider a fully detailed/struck coin far rarer than a coin with a mushy strike that details only the steps. Coins with mushy, worn out details are the pits, the dog do-do of coins and shouldn't have any place in anyone's coin collection but unfortunately, most don't have much of a choice monetarily. The usual plan is, a coin can eventually be upgraded...... maybe.
Also, don't be alarmed when you see a higher price on a coin that does not show in other price guides. That coin may have been upgraded 3-4 times and may have higher qualities than your average milled coin. The boldness of details usually play a role for such coins.
There are a few great books out there on grading coins including the The Guidebook of United States Coins by R. S. Yeoman, also known as The Official Red Book. Another is Photograde by James F. Ruddy.
The book, The "Jefferson Nickel Analyst" by Bern Nagengast is a good one.
And there are more modern books out there.
Drop me an email if you have any questions, at firstname.lastname@example.org