Doc, probably one of the fastest ways for you to learn quickly on what an MS66, 67, or 68 looks like, spend a little money for some lower priced "PCGS graded" coins. Perhaps pick up an MS66 graded quarter from late 60s or 70s so that you have a base line. Look at it under 5x magnifier to see what an MS66 grade looks like. If your quarter looks nicer under the same 5x, it might be good to send it in for grading. I've wasted a lot of good money sending coins for grading. What I'm left with is a nice library now of reference slabs that would have been way cheaper for me if I simply picked up other people's low graded coins.