I love Paint.NET! I forget how long I've had it, but I don't even miss Photoshop. Okay, maybe a little, but mostly because I haven't learned all of the dot net tricks yet. I tend to stick to the same techniques. But I've been branching out from pixel graphics and wanted to show the results.
This was a pencil sketch that I scanned into my computer. I colored it using Paint.NET. I do it the lazy way. I separate the different color sections (hair, skin, clothes, flower parts) into their own layers, create a new layer, fill it with whatever color I want that part to be and then mess with the Blending Mode, hue/saturation, and brightness/contrast until I have what I like.
Pencil sketches tend to be pretty light, so to get that inky look, I start out by duplicating the sketch, and using the Multiply blending mode on the top layer. It works a lot better than messing with brightness/contrast.
To get her tattoos to have that rainbow effect, I made a layer and filled it with different colors. Then I magic wanded the body and deleted the rest. The blue/purple skin was on a different layer, so all I did was erase the parts where the tattoo was, and the rainbow peeked through where I erased. Similar technique for the wings.
A nice, simple way to add texture to the color is to make a layer and use the cloud effect with two similar colors before messing with the blending mode. I did that for the flower petals and the pollen thingy.
I really like Overlay, Additive, and Multiply for this technique, but it depends on what you're going for. The first time I used this technique, the results were a little crude, but with practice, I ended up with this. I really like it.
I've seen people mentioning plug-ins, so I'll have to check those out. Take care!