These are the main sites/resources I use to improve my art and practice. Take a look, these might be helpful for you too! ^_^
I will add more later, these are the ones I can remember for now:
HUGE resources archive created by professional Artists:
Level Up! : http://www.fusroda.com/resources/
3d Total publishing: http://www.3dtotalpublishing.com/resources/
Creative Shrimp: https://www.creativeshrimp.com/resources.html
Useful videos to learn digital art:
CTRL+ PAINT: https://www.ctrlpaint.com/library/
Pinterest library full of references and tutorials:
Character design on Pintrest: https://www.pinterest.it/characterdesigh/
Color and