Putting at least a small space between the cards makes it easier to trim the cards, if they are touching and you miss the line by a little you will make one card too thin and another too wide. This size will allow three cards per each 8.5 X 11 inch sheet of paper. The cards I made were 2.125' X 3.125' when finished (so the rectangle in the drawing program was 2.125' X 9.375'). Then in the top third draw the values of the individual cards. If this image has a definite up and down remember to place it upside down. In the middle third draw the image of the back of your cards. In the bottom third draw a solid black rectangle, this serves to block any light that could otherwise pass through the paper and reveal it's value. So start with a rectangle that is 3 times as tall as you want the card. This gluing stiffens the three layers and makes them feel like a professionally made card.
In this method the cards are made of three layers of paper glued together.