How are you going to draw the units? In Paint or Photoshop??
There are many nuances to their creation, and it's very difficult...
You can edit a couple of demons in Photoshop, adding blue color...
The method of drawing units has long been figured out.
www.cove.woggrad.ru
Go to this link and then tell me how many units there are that have been redrawn from the old ones.