I'm not sure if there are other ways to determine the value of cards, but this is the way that I do it.  It's 100% accurate.  Both sides of the back of the deck are marked the same.  So for this explanation, I'll only talk about the left side of the deck.  I can do the entire deck in about 3 minutes.
First, as most of us know, the suit can be determined by the four full spades at the top left corner of the deck.  The suit is determined by the darken shade of the center of the spade.  The two horizontal spades represent the Diamonds and Clubs and the vertical spades are the Hearts and the Spades.
We also know that the value of the cards is determined by the half spades on the left side.  If you look at the half spades, you will see a one quarter spade at the bottom and another 8 half spade along the edge.  The quarter spade and the 8 half spade near the top mean nothing for determining the value.  The first half spade from bottom is a 2 and is only a 2.  The 7th half spade is a king and is only a king.  So that leaves the 3rd half spade to the 7th half spade for the card values 3-7 and 8-Q.  The 3rd half spade is either a 3 or an 8.  This continues all the way up.  4th half spade is a 4 or a 9........   
So how do you determine which is which?  I'm assuming at this point, that most of you see the subtle differences in the shading of the half spade to determine which one to focus on.    So let's say that the subtle shading difference is the 3rd half spade.  So is it a 3 or an 8?  Running out of room on this post, will send another in a bit.