Is that GIMP software worth a try?
12 years ago
I checked out the site and it seems legit for a free paint program, but does it have similar features to that of Corel PhotoShop? (which I absolutely enjoyed using long ago before that pc crashed and the backups were lost. Seriously, it was extraordinarily easy and convenient to paint with its awesome array of brushes)
FA+

I haven't used Corel PhotoShop, but Gimp should have the same basics of Corel.
I use Gimp's Paths Tool to make my lineart neat and smooth (really awesome!)
And I recommend getting version 2.6; the new version kinda sucks.