EDIT: Apparently you said you were aiming to make pixel art, i didn't notice xD. My post below is mainly pointed towards concept art.
I'm a beginner like you but I found CTRLpaint.com really helpful. It has really clear video tutorials by a professional concept artist (Matt Kohr) that are short but explain a lot. I understand a lot more now than I did before I starting using CTRL paint which is like 4 days ago.
He recommends focusing on the fundamentals and drawing from still life if you're starting out (all on real paper, because it's easier to draw on paper since you don't have to worry about learning how to draw on a tablet), and explains why. You can't draw a dragon if you can't draw a vase. You can't draw accurate lighting on a sea monster if you can't do lighting on a simple cup. And drawing still life objects is simple and helps you focus on improving a certain technique, without worrying about other techniques at that moment. And it's easier to spot your mistakes when you're drawing a simple vase than when you're trying to draw a head.
Basically a lot of confusing stuff is clear to me now. I used to think drawing 3d shapes as a guide was like, childish or for total beginners. But he explained why we do that, which is to be able to imagine the object in your head much better. Once you split say a coffee cup into shapes you can rotate it in your head and draw it from any angle from your imagination.
It's a little confusing where to start at first so this is where I began: The Unplugged series, following the exercises on paper. The order is a little confusing but I think the order is from bottom to top.
Again I'm also a beginner but I thought this might help.
Actually I just started making it a habit to draw my art on paper before I draw it on the screen. It's much easier when I have what I want the image to look like in front of me.
I used to be in exactly the same position as you, (I say used to, but i'm still trying to improve) and there are a bunch of things I could personally advise you especially as i've gone through the journey of creating 'crappy' work. I could KIND of draw from a photo or reference, but when it came to drawing without reference...the best I could do were stickmen! If you would like some guidance drop me a PM with some of your work so far (doesn't matter how bad!) so I can gauge what level you are at and give you some pointers that might help. The bottom liner is that hard work WILL get you to be better, however as you said - hard work without any guidance or principles is like eating loads of crap and wondering why you're not fit. I wouldn't say I'm 100% where I want to be yet with my drawing ability, but i'm getting there slowly. Check out my work if you like (http://clymsmith.co.uk) and drop me a line if you think that I could be of benefit to you.
People here aren't quite looking for concept artists. No project here is serious enough for it. What you could do is make sprites, backgrounds or ads for people, as that's what they want here. If you want do do concept art, I'd suggest you writing a good email with your portfolio included in it. Then send it to every game or movie company, or wherever you want it. You will probably be ignored, not that you draw bad, you might be Michelangelo, but they just don't check email. It's really, really hard to reach them via email, so if you are near their company, I'd take a walk.
Agreed. However My initial idea was for people who want to gather people onto their project could use a concept piece to "sell" their idea to get more people on board. Nothing like a visual piece to sell your idea to get coders, sprite artists etc to join your vision. I'm not really a sprite artist so I wouldn't be an asset for that side of things. Heck if there's no-one who would be interested in using my skills for their project then that's fine! Just thought I would put the invitation out there anyway.
The main goal will be to get in contact with games companies and art directors of movies but for now I need to build more of a portfolio (and improve obviously) that reflects a concept artist, because the majority of work is very stylized and illustrated - I have been applying to children's illustration agencies so fingers crossed for some work