I agree with dr bob, there is no repacement for knowledge of technique to support your own judgement. Initially, you will spend a lot of time and use a lot of paper in learning how to put on to paper the tonality and contrast you see as being the most expressive for the image you are printing. Once you know the darkroom dodges you will find that the only thing you cannot do is put detail into a shadow when it has not been given sufficient exposure at the taking stage.