In that case, I think you would benefit from practicing drawing basic forms (spheres, cubes, tubes, etc). Most objects are just a bunch of these basic forms put together, so if you practice drawing them from various angles and work to visualise them in 3D, you should have a much easier time visualising more complex objects.
I recommend doing this practice with pencil and paper or some other high-res medium you're comfortable with, so that you're not distracted with pixel techniques and trying to get the shape you want at a small size.