How to avoid the bad and the ugly?

Some great pictures of how network servers, both racked and unracked should and shouldnt be cabled. But where should we go to find out how to aoid the bad and the ugly? Its not enough to say it needs planning, what do we need to consider when planning? I know there’s no replacement for experience but are there any tools out there to help those of us that are struggling with tidying up somebody elses mess? Working with a well cabled network is a joy that makes everyones life easier and saves the owners money because we, as techs, dont have to hunt the other end of this or that cable. My clients are starting to realise this and are willing to invest the time and money into having other peoples botch-jobs put right, but where do I start?