Step 1: The Basic Sketch
Secondly I love for drawings to have a thick boarder, almost like comic book style. So go ahead and pick a dark thin brush, the equivalent in real life would be a fine point sharpie marker. My image only shows me doing the head but continue to do this throughout the body. Do not shade or add fine details with this brush.
Step 2: Shading the Zombie
I first start with the skin because it has the most variation of the entire zombie. Shading is an art itself so keep trying it until your happy with it. Remember you can go out on the lines and erase after because you created a new layer at the beginning of this step. Continue to shade until your zombie is complete!
Step 3: Adding the Peashooter and Basic Background
The process of creating the pea shooter is exactly the same as the zombie. It easier due to the fact that there is less detail on the shooter. So start the process. 1: basic sketch with a pencil, 2: darker out line, 3: SHADE!
For the background create yet again another new layer draw a basic road some grass and a hill and you got yourself a nice simple background!
Step 4: Adding the Fence and Detailing the Road
For the road and side walk to add some depth I added a simple curb. Its not much but it has a huge effect. Then I picked a textured brush. Which one is up to you, and went from dark to light and done, a simple road completed. Make sure you erase to shading that went out the lines.
Step 5: Finishing the Background
As for the sky I used what sketchbook pro calls A "Synthetic Soft Round Brush" but you can use what ever you want. To make the moon I used the ellipse tool to make it round and the shade tool ON WHITE to make it look real. For the stars just click on to the sky layer and use the eraser tool on the smallest setting and place dots everywhere.
And last but not least I used another synthetic paint brush on the side walk and made it very dark for variation. Then you background should be complete!