This is not written in stone, just a system I use. On my computer I have I have a form made up with 12 rows of numbers, 1 thru 10, 11 thru 20 and so on up to 120. The rest of the form is used for taking notes on what I find on the coin. Each number represent a Vam#. Most of the time this is way to many and on some not enough. For those that don't have the
VAM Encyclopedia, I recommend using vamworld.com. On the home page, left side you will find "Morgan vams by date". Left click, this will bring up the years and mints. Click on the year and mint your trying to attribute. This give you a list of Vams for that year and mint. Now back to your coin.
1. Date position and elimination.

As you can see from the picture, the coin I'm showing is a very far date. This allows me to eliminate all Vams except those listed as very far date. If the date was located in the normal position, this allows you to eliminate all close, very close, far and very far dates. The more you can eliminate the easier it gets.
2. Date doubling.

Here I'm using an 1882 as an example. Note how important it is to get clear close up pictures. Last 2 digits are doubled on this coin. Again this allows elimination of any Vams with doubled date, doubled 1, doubled 19 and so on. Often, specific doubling on the date allows you to go straight to the
VAM your looking for. If not, by now you've crossed off enough numbers that maybe only a dozen or less are left to make your choice from. Here is where taking notes as to the oddities on your coin helps. Die markers are very helpful with the attribution. Die scratches, polishing lines, gouges and other abnormalities can lead you to a match.
3.Mint marks and position.

Using the chart, you can see the coin has a high mint mark, upright and centered. Vams with mint mark tilted right or left, positioned right or left and normal are all eliminated. As you can tell by now, I'm not a big fan of looking at every
VAM listed trying to match one up to mine.
This is not a fool proof method, but should get you close enough to have very few Vams to choose from.