I can say without question, the best thing to do is control your lighting and make adjustments BEFORE your film is exposed. Darkroom magic and computer manipulation are great tools, but it is extremely difficult to overcome bad lighting. I was a portrait and wedding photographer for many years, but I became much better at making good, well lit negatives once I started doing tabletop product photgraphy on chrome film which is completely unforgiving to exposure and lighting deficiencies. Get it right on the negative, and your darkroom and post production work(which may or may not include photoshop corrections) will will become vastly easier.