Protoscience is to be distinguished from pseudoscience by its adherence to the Scientific Method and standard practices of good science, most notably a willingness to be disproven by new evidence (if and when it appears), or supplanted by a more-predictive theory.
Most typically a protoscientific field is one where the hypothesis presented is in accordance with the known evidence at that time, and a body of associated predictions have been made, but the predictions have not yet been tested.
Examples of protosciences might be the theory of continental drift as originally proposed by [Alfred Wegener]? (which eventually became an accepted scientific model when the mechanisms of [plate tectonics]? became understood), or the various string theories of physics.
Such fields as acupuncture and lucid dreaming may perhaps be best categorized as protosciences, pending more evidence and theoretical underpinning.