Hi, Allyson!
I've been working on the same goal recently, trying to make my art less stiff. Since the start, I've always been used to starting my drawings with a basic skeleton, so that's the method I've been using. But skeletons can make your art VERY stiff, especially if you think of the bones as straight lines, as I used to. So what I've been doing that has been working for me is trying to draw the skeleton itself with more flexible lines. Like, instead of straight lines, I'll make slight curves, making sure that they change at least slightly at every joint. That has been helping me a lot!
Another thing that has also been helping me is making my sketches really scribbly (so drawing more lines, instead of fewer lines, haha) and starting with very light lines. I feel that by doing that, I give myself more options of lines to choose from when I start refining the pose.
Another technical aspect that I've modified that has been helping me improve really fast is that I've started to draw in the beginning by moving my elbow or shoulder, instead of just my wrist. I know that sounds weird, uncomfortable, and clumsy but it's a wonderful way to make sure our lines are more fluid. This is just to get started with the drawing, like, when you're establishing the line of action and the position of the main elements of the figure (head, ribcage, hips). I got this technical tip from this Youtube video. I think you may enjoy it, too:
Line of Action and Technique
Again, I'm by no means an expert. I'm just a student that has been working on the same thing as you are. I just wanted to share what has been working for me. Hopefully, at least some of what I've said will work for you as well. Keep drawing and having fun with art! Best of luck!
