You wanna see my drawings? No? Well too bad I'm showing you anyways! Lol :P
The only reason I'm posting here instead of on deviantART is because no one comments on my pics to give them critique >.< Just a warning, they pretty much all suck lol
Your drawings don't suck. You just need to work on proportions a little bit. It's really hard, but once you get the hang of it you'll be incredible.
Try drawing some more off photo references, that will help hugely. Pick one that's got really strong shadows and highlights, and draw what you see. Just the shapes. Draw in the shapes of the darkness, then work your way through the shadows and midtones until you draw in the highlights [I'm naughty and do it the other way round a lot]. It really helps with your shading.
Here's an example, sorry it's not horsey [photography is from jasonaaronbaca.deviantart.com and is stock]. VERY heavily referenced off the photo, because I suck at drawing people.
Original stock image:
Edited to this:
Highlights blocked in:
A few more shades, he's starting to take shape:
Followed the same approach through a further 10 layers [probably 13 different shades all up] and got the finished product:
I'm not totally happy with him, I want to tweak his back and his face some, but considering I only "drew" him to illustrate a concept to my cousin, I think I'll leave him be.
You can also do it in colour, but I find that a lot more challenging.