It certainly is cool to meet someone else with a passion for making small top-down military images!
Yes, I like Paint.net, but after finally wrapping my mind around GIMP, using Paint.net feels like using my mouse with my left hand! I'm going to need Paint.net because GIMP's been acting up lately--there are so many strange aspects to that program!
Here's an example of what I'm trying to do:
I want to translate some images to be in SP. I changed the paint scheme to be more SP friendly. It still looks too dark to me, but I'm just starting to learn. I must admit, this is a challenge with such a limited palette!
I'm planning to play a long campaign, and replacing each icon as I encounter it. Most of all, I want the game to feel like I'm actually playing with little metal miniatures!