Certain models like skeletons or necrons require very little fine motor control to paint to a reasonable standard.Yeah, dollar stores also sell similar miniatures. My biggest problem will be keeping may hand still as I have some nerve damage from when I young. That, and my poor eyesight but I can get a magnifying glass for that. Really good ones out there with LED's.
For a skeleton, if you simply paint the whole model a bone color, and apply a brown wash, followed by an eggshell drybrush and a single layer of silver/bronze for the weapons, with some dabs of orange/teal for rust or verdigris and fonally some brown for the weapon hafts, you're good to go, and you can be as sloppy as you like.
Nids aren't much different. You really only have to be able to paint the flesh and carapace separate colors.