Some of my lessons learned:
* Whatever you do, be very mindful of future events (repairs, replacements, etc). Spending an extra 5mins upfront when you are in a hurry will save you lots of time later.
* Label each end of the cable if possible. It is a PIA in the beginning but will be a real life-saver when you need to do maintenance
* Replace old (fat) cables with new, thinner cables of the proper length when possible. I typically add 1ft extra to any cable for a little slack.
* Think of airflow. Lots of cables bundled in the back of a rack can seriously cause airflow issues. Try to run all cables along the sides of the rack.
* NEVER run cables across the back of gear - especially for multi-node chassis that require rear access for maintenance
* Velcro is your friend.
* Stick with a cable color standard if possible. For me, I use white for IPMI, blue for data, red for external access
* Keep an updated diagram in the rack for the next guy/gal who needs to do work
* Always remove old/un-needed cables after a maintenance job.
* Keep the rack clean!
We're in an ongoing battle with abandoned-in-place wiring in our current building. There's data wiring back to ARCnet (93 ohm coax), and power wiring going back to knob and tube days.
ooo nifty. be on the lookout for vampire taps. they never truly die.
800A 120/208Y service entrance conductors live in the same raceway as 20A branch circuits. I got shocked off a lighting circuit with the main open once.
This is a former The Power Company building. I always heard it joked they could only use leftovers from customer jobs on their own stuff.
One building we were in had Twinax above the drop-ceiling (used for System-36 and AS/400 terminals). Plus dozens of multi-pair phone cables that had been left there. I wish I had all that copper now that prices are much higher.
Making your own cables that are the exact length they need to be instead of using preterminated ones and just stuffing the slack into the side of the rack, routing them down the side and through the floor or the cabling trays on the ceiling, standardized naming schemes for labeling devices/ports on either end of cables, documented rack diagrams, etc.