I like CamelCaps as they're called (capitalizing each word instead of spaces or dashes) and generally go DateDesignDenominationObv and DateDesignDenominationRev
So a US 1804 Draped Bust Half Cent obverse photo would be 1804DrapedHalfCentObv
A Canadian 1859 Queen Victoria large cent reverse photo would be 1859QueenVictoriaLargeCentRev
I don't normally specify country because my photos are all organized by what set they are a part of, so having a folder where every file name has "Canada" would be redundant for me.
So a US 1804 Draped Bust Half Cent obverse photo would be 1804DrapedHalfCentObv
A Canadian 1859 Queen Victoria large cent reverse photo would be 1859QueenVictoriaLargeCentRev
I don't normally specify country because my photos are all organized by what set they are a part of, so having a folder where every file name has "Canada" would be redundant for me.