I'm going to create a cartoon looking cat with the GIMP, true, you can get the same results with Inkscape but, Inkscape runs poorly on my computer. Plus, with practice, I can create these animals just as fast with Gimp and without bogging down my system.
I'm going to do this tutorial in steps so I dont have to upload a million screen shots at once but after reading the tutorial all other steps are the same for finishing the cat.
First I want to point out that I tabbed all of my most used dialogs in the main toolbox window. It took some getting used to but I wish I had done it years ago.
Step one, open a new image that is 400x400 and transparent background.
Step two, with the "ellipse select tool", click and drag to create a circle selection and position it below center so you have room for ears. NOTE...holding down "shift" while dragging the select tool will create a perfect circle. (this also applies to "rectangle select tool" giving you a perfect square). Fill in the circle with the color of your soon to be cat.
Now, withe the circle still highlighted, choose "select" from the top tool bar then "shrink" and from the dialog that pops up choose 4 pixels then click "OK". You should notice that the selected area is smaller than the original orange circle. This will create a sort of boarder.
image 4, 5
Next, choose the "blend tool" from the toolbox. In the "blend tool" dialog, choose FG to transparent. Pick white as a foreground color, then drag the blend tool downward from the top to create a highlight like the image below. NOTE...holding "ctrl" while dragging the blend tool will draw a straight gradient.
Repeat the process for the bottom but change the foreground color to black and the gradient opacity down to about 45.
Press "Ctrl+Shift+A" on the keyboard to deselect everything. In the "layers dialog" double click the background layer and change the name to "head". Create a new layer and call it "snout". You should now have two layers, one with the orange head and one that is blank.
Make sure the "snout" layer is active by clicking on it in the layer list (active layer is highlighted). With the "ellipse select tool" create a much smaller circle only this time don't hold "Ctrl" so that we end up with an oval shape and not a perfect circle. Fill the oval in with the color of your choice. Position the oval down where a cats snout should be but make sure that the right edge of the oval is past the center line of the head so that the two halves of the snout overlap in the end. Next, hit "Ctrl+C" to copy the oval "Ctrl+V" to paste it then choose the "move tool" and click inside the oval to tell the move tool what to move (be sure not to move the selection while clicking) Now you can use the arrows on the keyboard to precisely move the selection to the right. Then click the "anchor" icon at the bottom of the layers dialog to set the pasted layer in place.
Notice how nothing is selected anymore. We can fix that by "right clicking" the "snout" layer and choose "alpha to selection" from the menu list. Now, with the whole snout selected, repeat the same process as with the head. Shrink the selection by 4 pixels, apply a white gradient to the top and a black gradient to the bottom then "Ctrl+Shift+A" to deselect everything.
Create a new layer and call it "chin". Now the fun part, creating non typical shapes. I normally just eyeball this part so I'm going to use the "zoom tool" and zoom in where the chin is going to be. With the "ellipse select tool" select a circle. Focus the size, shape and position of the circle in regards to only the bottom curve of the chin.
With the circle highlighted and positioned, go to the "ellipse select tool dialog" and change the "mode" to "subtract from the current selection". With the mode changed to "subtract from the current selection" we can draw a new circle selection and when that overlaps the first selection it will subtract the overlap. set it up like the image below then hit "Enter" when its all in place. Repeat the process with the other side of the chin.
Fill the chin with the same color as the snout then repeat the same highlighting process that we did with the head and snout. Only this time, shrink the selection by three pixels. When the gradients are done hit "Ctrl+Shift+A" to deselect and press 1 on the keyboard to reset zoom.
I'll stop here for now but as you can imagine, the eyes ears and cheek fur are all created the same way.