Thankfully, Minecraft's pixelated graphics and geometric shapes make the creeper one of the easiest patterns you will find. For my pattern I translated every two pixels into one inch.
Head: 4" X 4" X 4"
Body: 2" X 4" X 6"
Legs: 2" X 2" X 3" - Make four of these
Map out the panels for each side of these boxes on your fabric. Be sure to keep about a half inch allowance around the edges of each outline. Keep in mind that you do not need to cut out the top side of the body because it is closed off by the creeper's head.
When you cut the pieces out do not cut along the lines you drew. Instead, cut about a half-inch to a fourth-inch outside the line.
The pieces should be easy to recognize, but if you think you will have trouble mixing them up I suggest labeling each part, or cutting out only the pieces of the section you are working on.