for a more textural and/or painterly result try Krita https://krita.org/
As a whole though I'd recommend getting a copy of Photoshop, legit or otherwise, to learn. It is the industry standard in image production and editing and knowing your way around it will payoff in the long run.
Comments
for animated and still pixel art I'd recommend graphics gale http://www.humanbalance.net/gale/us/index.html
for a more textural and/or painterly result try Krita https://krita.org/
As a whole though I'd recommend getting a copy of Photoshop, legit or otherwise, to learn. It is the industry standard in image production and editing and knowing your way around it will payoff in the long run.