gonna go ahead and start by throwing this here .
http://www.polycount.com/forum/showthread.php?t=137585
now that that list links out of the way my personal favorites keep in mind im a landscape artist sooooo yea.
https://gumroad.com/onepixelbrush - THIS This is the single best tutorial i have found. everyone and i mean everyone should buy this one, it doesnt go over painting practices or techniques but is instead a talk about what mindset you need to truly improve the most inspirational video ever for a artist, i watch this often.
https://gumroad.com/eytanzana - guys a genius at light and photo incorporation into a painting
https://gumroad.com/abigbat - landscape stuff great color choice <3
https://gumroad.com/noahbradley - Stock art talks and other things
https://gumroad.com/tituslunter - Art talks and other things
a lot of the tuts i buy will often be art talks as i think its more important to learn the proper mindset you need to be in to make art rather than a way one artist may do his process, because everyone's process is different and there is no right way