Find an old sock that fits your hand snugly.
Slip the sock over your drawing hand. You will be cutting the glove along the lines shown below (after you remove your hand of course!)
Here's what it will look like after cutting
Turn the sock inside out and stitch along the finger seam to create a pocket for your little finger.
Here's how it will fit after you sew it.
Now you can draw on your iPad without the side of your hand making random marks on your drawing.
Note: I'm not sure all socks will work. You can try slipping it over your hand and gliding it across your iPad to see if it does before you cut it up. Good luck!