This first one is just a ten minute random doodle I did when I was bored, not a sketch for a larger drawing, but it shows both the cleaned up, finished look of the sketch, in the head and torso and upper arms, and the very chaotic unfinished phase from when I first start sketching, in the legs and hands:
I didn't really have an idea in mind for this one, I just started drawing random sketchy lines, and this is what it turned into. Still, the process is pretty for all my sketches, whether or not I have a clear idea of what I'm drawing beforehand. When I figured out what I was doing, I mainly tried to capture a sense of movement in the sketchy lines, to make it look like the figure was stepping forward, and I tried to convey a sense of purpose, pride, and otherworldliness in the figures body language (I'm not sure how well I accomplished this). I've found that this sort of thing is much easier to convey with lots of loose, fluid lines, and then slowly refining them, keeping and strengthening the lines that have the most movement to them, if that makes sense. I kind of feel like sketching like this is sort of like carving a sculpture, where you have a rough shape to work with, and you slowly refine and shape it until it's what you want it to be.
Here's another example of a rougher sketch, this time a little thumbnail sketch for a digital piece. Again, I was mainly trying to capture the movement of the dragons wings and pose (ignore the 4+ tails, I was trying to figure out which tail position I liked best and ended up making all the lines too dark, and didn't feel like erasing it).
These are a couple of sketches that I did for one of the main characters of the novel I'm currently working on. I had been trying and failing to draw him for ages, and these sketches are the first ones that I managed to make work. I mostly focused on trying to get the pose and body language right, to get his personality across. Apparently I succeeded, since I asked a friend to describe what they thought his personality was from just looking at the sketch, and they nailed it.
And if you want further reference on how I do it, here some mostly finished sketches, most of which will probably be turned into more complete drawings at some point or another. For all of them, I tried to focus mostly on getting the movement, pose, and anatomy right with the initial chaotic lines, and once I think I've gotten that down, I start to refine the sketch and figure out the details.