The main skill in designing PCB's is component placement, the success of the design depends on good comp placement, the rest should then follow. Autorouters, very very rarely use them, may use them interactively for little areas and to get a metric on placement but that is it.
Some analogue digital design links, mainly relating to ground and how to placethe components... http://www.hottconsultants.com/pdf_f...ixedsignal.pdf