Weedgoku: In addition to what HH beat me to:
I think if you rely on two spheres like I do, it might help to make the front circle around half the size of back one and make sure the two are at least touching from any perspective. That way when you hang the front legs on, they're much more likely to be near enough to the back ones. (Just look at how close together they are when on-model.) The two circles will look like a pear at first, but once you make the neck flow smoothly into the pony's back circle you should easily end up with a good bean shape.
A thing to get to know is that FiM ponies are compact, taller than they are wide but managing a pretty short neck. (despite real ponies being almost the opposite) Their head and legs are huge, giving them something like 70-80% of their height, while their body is just the little bean those sprout from. You could make it much smaller than it's supposed to be and it'd still look fine, but there's not a lot of room to make it bigger. (This seems to be a rule for almost everything that serves as a connecting point in cartoons. We tend to interpret it as huge heads/hands/feet and whatever else, but that doesn't often hold up when you compare a cartoon character to the environment they inhabit.)
IWF: You seem to have the same problem I did at one time, getting too caught up in the end quality instead of how well you're doing on first pass. I can't entirely tell, but it looks like your first sketches are being made by drawing out certain body parts without any guide lines to help plan and mold things. Your black lines also seem to follow them pretty rigidly which makes me think they're treated as just a first attempt with one layer of improvement. As tempting as it is, cleaning all those overlapping lines from a sketch and fixing mistakes isn't worth the time it takes. There's only so much you can enhance by making corrections as opposed to actual redrawing and refining.
What I suggest is to force yourself to sketch a lot of different poses and things very quickly, allowing your mistakes to just be there
. You won't actually be making a lot more this way, just leaving the ones you did. This is efficient practice because you don't get better by making a correction but the mistake itself. There's no need to make the individual strokes very fast or in one sweep, and you don't want to be 100% careless, but up your pace as much as you can. Undo if you want to retry strokes, but don't touch the eraser. Your only choice should be to start anew or keep going, because you want to be drawing
the whole time and not fixing or tracing. (Silly Tetris Analogy #2: You can't avoid losing, but score as many lines as you can before the playing field becomes an unworkable mess.)
Preachy conjecture stuff out of the way, I put my all into refining that last pose, and by that I mean I just rebuilt it more carefully:
I am at my wits' end with those front legs. I tried putting them everywhere before I realized they absolutely couldn't be flat (they would just look twisted or dislocated) and this was the best I managed thereafter. I looked at all kinds of guides and references but joints + depth =
This has been a very long-running issue with me and art. I can pound a specific configuration of 3D shapes into my head until it translates to 2D, but move or reshape something even slightly and it's back to feeling around in the dark for where the creases and stuff will make sense. Imaginary depth is a big bad bastard.