Tips for an initial buildout

St Aardvark the Carpeted (best. name. EVER.) has been working on building out a new data site for one of the companies he works for. He's got some great tips on things to remember and take into account before you do one of these yourself.

I know the installers that built my most recent rack at the colocation really appreciated the
layout that I made to show what was going where in the rack. I also prepared spreadsheets listing all the cables and where they went. The colocation also needed all serial numbers to all equipment that I was bringing in, which is good for me to have anyway and is probably a good practice to have on hand.

Has anyone else got any tips for a one-time build out that would help?