I thought posting this link might be helpful and also explain the process. Counting and knowing the results is only half the battle.
You must then know what those numbers mean.
The book "The Garter Snakes: Evolution and Ecology" serves as a good source for what snake/s match up to the scale counts found.
Here's an example from the book.
This is for Thamnophis marcanius (Checkered Garter)


How to count scales
head scales