There are a lot of covers described in the exhibits on these pages for you to look at:https://www.rfrajola.com/exhibits.htm
Basically, I think you're on the right track. I might just add the year and denomination in front of your "types" when describing the stamp, such as 3c 1857 Type II or 24c 1861 grey violet...
You can also try to figure out a basic set of headings and sub-headings, as well as a standardized format for the description.
Above the cover:
Headings - 1861 Issues, Foreign Mail, Circular Mail, Free Franks...
Sub Heading - Circular Mail, Patriotic Use...
(or some combination of the above - heading is the broad category and the sub head is the key thing about this cover within the heading category)
Below the cover - a standardized format:
First paragraph - From, To, Date. Basic description of the cover
Second (optional) paragraph - Description of something unusual about the cover you want to point out (such as the description of the Patriotic above)
Third (optional) paragraph - Census (e.g. "one of three known," "earliest use of this cancellation device" ...), Provenance ("ex. Gross"), References ("illustrated in Brookman, Vol. 1, p. 321"
Hope that helps.