Hey, @Canyon Braff! I agree with @sharksidian, drawing from life is often a great practice for most artists. But, since you objectively mentioned you want to improve your skill of drawing from imagination, I’m afraid that just sight copying images should not get you as far as you’d like. While copying is a great way to practice our skills of observation (and that is a valid goal as well), I believe that the best practice we can invest in to improve on drawing without reference is… to practice drawing without reference. For example, let’s say you want to spend a few minutes practicing drawing a female figure wearing a dress. Instead of just grabbing a photo and copying what you see, you could try this: imagine the pose, sketch the gesture and basic forms of the figure, then try to construct the dress on top of it, figuring out how things would work regarding form, weight, tension, wrinkles, compressions, gravity, texture, overlaps, folds… and then, when you find yourself stuck in some part of the drawing, you can take a peek at photo references to get a visual clue of that specific part - but, then, keep on working as independently as possible from copying the reference. In other words, see if you can use references as a “cheat-sheet” to help you solve drawing problems more so than something to just mimic entirely. Of course, for this kind of imagination/memory practice to turn out successful, “theory” and previous knowledge of the fundamentals serve as a solid ground to stand on. In the example I described above, it would be essential to be familiar with the basics of figure drawing (gesture, the Bean, the mannequin, balance, proportions, a bit of perspective and anatomy) and the basics of how drapery works (tension points, gravity, folds, wrinkles, materials). But don’t worry if this sounds like too much right now - since you mention you’re on a “beginner/intermediate” level, perhaps you haven’t studied all those topics yet, and it might be too soon to expect your practice of drawing from imagination to rely on so many different bits of information. So, if that’s the case, just be patient and keep studying and doing exercises and free practices while also remaining aware that, as you progress in your journey and get more confident with your basic skills, you might want to gradually experiment letting go of copying in order to head towards your goal of being able to draw from imagination. Hope this helps!

I'd recommend looking for real-life figure drawing classes in your area. Dealing with 3D forms in person vs a 2D image of that same thing is a huge, huge difference (even if it sounds similar), and if you're stagnant it might be what you're missing. If that isn't feasible, I'd recommend making a few still lifes with stuff you have at home so you have some experience with drawing from life at least.