>>12210356Your colours are a bit uh, plastic? Like, gooey plastic. Your shading is boring in the colour choices and looks dirty in places instead of being shadows. The main thing you want is to stop always using black, white, or slightly light/darker of the same colour.
The lines are very bold and flat. You're starting on some line weighting, fiddle around with the minimum size and pressure of whatever tool you're using to do your line work - more delicate parts get more delicate lines, the bold and big get thick lines. Also play around with using colour for your lines instead of pure flat black. Don't feel you HAVE to make every line a different colour, sometimes just using a blue/brown/purple is cool.
Just gotta check - you're not using smudge, burn, dodge right? These tools warp the colours of your piece as well as rob you of opportunities to build on the feel of your picture.
http://fav.me/d52omh6Obligatory point to the pastebin resources! Go exploring all through those links, the /ic/ website, the tutorial sections of websites. Heck drawfags on tumblr reblog some lovely stuff if you don't outright follow any of the tumblrs dedicated to art resources.
Always remember it's more than ok to reference and read up on what it is you want to draw. The more you read on the more confident you can be in what you practice.
