Focus on what you enjoy making the most, because that should be your goal. If you don't know what you enjoy, I dunno o 3 o
But aside from training in that which you like, you also need stuff like "painting pretty colors" "understanding how shadows fall on stuff" "anatomy or how things are constructed" and "painting the places where things exist" and such. Like, all-around drawing skills. For example, I don't care if you only ever draw cartoony things if it teaches you anatomy while you're at it. But if you do it to avoid anatomy, that's not gonna go well.
If you absolutely feel hopeless with detailed construction:y drawing, I suggest tackling everything from a 'design' and 'layout' angle - learn how to make abstract yet good-looking graphic displays of ratios and colors and the best ways to stylize things you think look good. I mean stuff like
http://indiestatik.com/wp-content/uploads/2013/02/1440.jpg and segue into stuff like
http://static3.businessinsider.com/image/5311fbd069bedd0928f07868-1200/threes-tells-you-at-the-top-what-kind-of-card-will-be-added-next-at-the-game-board.jpg and
http://www.bermuda.ch/balduin/blog/Loco_Roco.jpgbut beware, because loco roco and threes are absolutely drawn/created by people who absolutely have a good skill in drawing. I'm just saying that learning how to combine big flat fields of colors in a beautiful way is never going to be a bad skill!
but I'm not actually suggesting 'that style', just thinking out loud. still my tip is 'learn everything about art that you possibly can, related to games or not and practice what you find the most fun'
... you can do like me too, and learn pixel art if you want to! Pixel art is really good, it scales from abstract atari-stuff to SNES and even 90s arcade game complexity. If you get your skill level up to SNES chrono trigger ability (while sketching a lot on paper mind you) you'll develop all the skills you need in a very condensed and limited environment, which will hone your graphic senses. At least that's what I think, cause that's what I did.
Good luck anyhow
That's a great reply, thanks
Well I've done a bit of game graphics work over the years
http://www.biggerplay.com/game-graphics but yeah you're right I don't really have a "style" I just alternate to what's needed, but I think it would be good to become really good at one particular style, rather than being "ok" at a lot of them maybe? or maybe it's better to be a jack of all trades when it comes to getting game art work, that to me is more what it's about right now, the getting work point of view rather than the become a particular style expert although that would be cool
.... I love pixel art, I was actually messing around with game development when pixel art was actually the main style! (I'm very old :p), the only thing is, if i spend a lot of time becoming good at that I don't want that to mean when other styles of graphics work comes up I'm in the best place to take them.