I made that one in MyPaint actually. I have a ton of software brushes that I downloaded for it. I have the Gimp Painter, and have messed with it, but there are so many settings that it's a little bit daunting. I'm starting to get more comfortable though, so I'll probably be venturing into it more in the future.
it seems daunting but it really isnt.....
work in layers, the layer tree, mine is on the right side, it will load up with just one layer, say you have a color that you want to deepen, but dont want to add more color....make a duplicate of that layer..then merge them together(to work right they must be in the same "mode"if merging from anywhere but the second from bottom...
Right click on the layer in the layer tree...this will give you options to duplicate or create new layer....a new layer can be any color you want or transparent, which is what I always use for new layers unless duplicating of course....
when you merge layers start from the second from the bottom so when you are done they merge with the bottom layer, but only do that for finished stuff, if you merge anywhere else you will lose the "mode" set for that layer, IE if you try to merge down a layer that is set to "burn" anywhere in the layer tree (except the second from bottom) it will go to "normal"....and you will lose the "burn effect"
also keep a copy in native GIMP format with all the layers so at any point you can go and work on an individual layer....
you can find an absurd number of brushes for GIMP painter also..... GIMP brushes are fine for GIMP Painter....
and you can make our own brushes also
a thing that gave me a hard time was, I would forget I had something "selected" and try to work elsewhere on the image or another layer outside the selected area...when you have a selected area you can only work in that selected area but on any layer.
the tools that are up top can be gotten to by right clicking anywhere on the image....
also there are "windows" such as the layer window that can be docked, click on "windows" or right click and choose "windows" I have
the layer window....the selection editor window....history window....Paths window..... and channels window all docked
(if you do skins the "path" tool is a must for rivets)
experimentation is a great thing and a fast way to learning
