Getting Started \ Best Practice Guides?

The organization i work for started using service desk plus a while back, long before i started. There was never anyone that owned the responsibility of administering it or setting it up correctly. For instance my service catalog is Accounting \ IT Operations \ Application - there is nothing under those, they were more used at categories.

Really we need to start over, but i'm having a hard time finding any documents on best practices or even a getting started guide. Like for instance is it best to have a good service catalog before i start tinkering is the helpdesk settings? I'm assuming so. I just need help getting started instead of tackling each piece alone.

Thanks,