Here is small tutorial for drawing a goblin avatar. You will need a vector drawing program (I use inkscape a very nice and free program) and know the basics of how to use it.
First of all we start with the eyes.

Now we make a copy of this and we have two eyes, for stereoscopic vision.

For the head we do a big green circle and fill it with a radial gradient from green to very light green. The center of the gradient is set to the top left of the circle to represent the glow. We also paint a semi-transparent small circle in the center of the gradient to put more accent on the glow.

We place the eyes and the goblin is almost done, we just need ears and a mouth. The ears are simple, we start again with a circle and cut a part away by difference with another circle. We use the edit paths tool to make the shape more ear like and we fill it with a gradient. The ear is done.
The mouth is nothing more than a small circle filled with a gradient.
You can easily make variations of this to draw other creatures such as cats, dogs, pigs and gremlins.
Here is what the end result looks like (with some totally useless scanlines added to the final picture to make it look like something from the good old Amiga days).

We are done.