Procedure and Policy should be 2 separate hand books. I really can't add to what others have said to policy, so yeah +1 to above.
Procedure ... be as anal retentive as you want in the steps. The few I've written up ended up about twice as long as I thought after I added in all the small details. Oh, and when that gets written ... realize that all your files on your computers will basically start at 0 since there is probably a mess of mismarked jobs, lost proofs and junk art. Make sure you have it all stored on a networked and shared computer so all the stations have access to looking for old art and make sure they save it with the new file formatting.
One I wrote, the shop was having a huge issue with old art being used, so I had to start formatting the files (Invoice)-(Persons Initials)-Name-(Date)-(version) with version being labeled proof=PR#, Revisions=Rev#, and Finals being labeled FINAL (in caps.)
So for example, the shop owner would save his files as 58234-RH-MashupShopPoster-6-23-13-Rev13.cdr which would be different than the designers 58234-MN-MashupShopPoster-6-19-13-PR5 and you would know just about everything about the job if someone was going from the invoice # of 58234 and even though the files were similar ... you could tell who did it, when it was done, which version of the art it was and what the art probably was just by descriptive names in the file. ... especially in the case where there might be 2 different designers working on proofs, they might both be labeling files the same let alone if someone just changes the initials on the file so there might be three Rev13's but with the date and initials being different ... can track down the right one.
While that was a simple explanation ... my detailed write up about it was about a page and a half long. I had another 8 or 12 pages of how to properly save files for importing into other programs, and how to label those, proper pdf formating requirements, how to set up manditory safe areas on files so even the non-designers can't **** up a file, prepress requirements for in house printing as well as out of house printing, how to prep art for clean CNC, Design resource listings in the shop, and a whole slew of other things that seemed pointless but since I did it day to day to day to make that shop work effectively ... I put it in there. ... and that was just on the computer. When I moved away from that city, I was also allowed to take my last week paid completely at home since I didn't really have to train someone on how to do everything the shop needs ... it was all in the Manual for the shop I wrote out.