I think most artists feel that way a lot of the time.
Don't do aimless practice. I mean, it's one thing to say it, one thing to actually do it, and aimless practise is better than no practise at all (although sometimes you might go on for long stretches of not picking up a pencil and then when you do, you're magically better) but if you can, set schedule and work on your weaknesses from the ground up. Anatomy and human posing never ends, really, no matter how good you might think you are at any given time. Draw from reference a lot. Don't trace, rather stylize and reinterpret. Draw buildings, everyday objects, this will help you stop thinking the world in terms of naive symbols (a human face isn't just 'eye' 'eye' 'nose' 'mouth') and more as the complex constructions of volumes (blah, I can't express this) they are.
As for pixel-art specific, as it was said, study good art you like from games or demoscene, but don' get obsessed with understanding why they do as they do. Don't try to 'do the things I do'. I'm not sure what I do, if someone pressed me to explain, I could give half-assed theories behind shit, but in the end I 'do' what I do, and after the fact, I rationalize it. How we work is the product of very interactive holistic constructs, everything interfaces with everything. Artists do as they do not because of pixel art reasons, but because of a design aesthetic that's well beyond the specific pixel art method. You might learn antialias and dithering and whatever, but the big battle will always be construction and content, and that doesn't have to do with the art medium, but how ripe your aesthetic is in your head. To get there (or on the way to there) actively soak up images. Reality, art, imagination. Be very aware as much of the time as you can. Look at a tree on the way home. Look at it from different angles, see how light works on the different surfaces. Try to soak in the resonance. Go home and draw it.
I am telling you all this, and I don't consider myself very strong on any respect. I'm not trying to preach as if I'm good. I feel most of what I said works to degrees for most artists, struggling or accomplished.
And if I'm allowed to say a final thing: there's no shortcuts. Don't hide behind an immature 'style', never rip art, never try to get good for the social benefits only. I'm sure we all do, but there should be something else driving, ultimately, some sort of feeling of accomplishment when there's expression going on. You should be the one to always challenge the trappings of your 'style'. Don't become warped-anatomy-dude-who-always-draws-the-same-character and don't become my-only-desire-in-life-is-to-do-fighter-sprites-like-KOF-guy and don't become lol-I-am-breaking-down-barriers-with-my-abstract-half-finished-art-guy either.