[GeeTwo]

Our wiring has definitely improved over the years. While we still won't win any awards for neatness, we have improved year-over-year (except rookie to 2nd year) in terms of shorts, loose connections, accessibility, and labeling. [Edit: After suffering from TRS (Twitchy Robot Syndrome, that is partial or complete robot paralysis in at least half of our matches) in 2013 Ultimate Ascent, we had zero electrical faults during competition in both the relatively benign 2015 Recycle Rush and the thoroughly brutal 2016 FIRST Stronghold.] These are our big lessons learned over the years:

• Have a wiring sub-team. Our first two years, the programming team did the wiring. The first year it was not too bad (partially because the robot was monstrously tall), but the second year it was jammed into way too small a space with even less access, because wiring was an afterthought. If you have a team member who is gifted at organization and documentation, or who is a "whole picture" person, try to get him/her on wiring. Because the wiring group literally connects the programmers to the mechanical team, this is a perfect position to coordinate, document, and communicate the overall robot design. OBTW, we have had better schematics than mechanical design drawings, and I'm in no hurry to change that --I'd like mechanical to catch up, but I don't want electrical to fall back to achieve it.
  
• Plan the board as though you will remove it and replace it regularly, even though you probably never will. Thinking through connectors as though the board is replaceable makes it much easier to replace any single component. Our third (Aerial Assist) robot was supposed to have a removable control board, but once we put it in place (in the belly pan, which I agree with MrForbes is a bad idea), we never actually removed it. It was still much easier to manage when we made changes, so we continue the fiction that the board is removable.
  
• Because the board will not actually be removed, make it accessible, and make it easy to shield from swarf when the build team decides to add on that super-whamo-dyne manipulator at the last minute. The last two years, our control board has been at the top of the robot, roughly facing the ceiling, covered by a polycarbonate cowling. (The battery has been low both years.)
  
• Thoroughly qualify crimping and soldering students, and inspect connections just as thoroughly. One of our control team catch phrases (borrowed from an IBEW phrase, I believe), is "LCKR (pronounced locker): Loose Connections Kill Robots".
  
• Whenever you have a choice, select a polarized connector. Anderson Power Poles are our favorites for wires carrying more than 5A, and Molex for smaller wires.
  
• Label, label, label. We have successfully used general Dymo labels, number labels, and the "resistor color code tapes" from 3M. We've found that the value of the labeling has far more to do with how well and consistently you use it than what labels you select (unless, of course, they fall off, in which case they're worthless!). Caveat: If you have a color blind member on your wiring or pit team, don't depend on color labels.
  
• Hinged panels don't really work out. This was the first year our control board was mounted on hinges. Despite repeated explanations that all wires must pass through this gap, only half of them actually did. We had to re-run a few connections to allow us to change the battery, but we wound up not re-doing a lot of others that really should have been torn out and replaced.
  
• Use the correct length of wire. Except for wires left at their COTS length to comply with those rules, measure all wires to be long enough to reach from one end of their path, along a well-defined (mostly rectilinear rather than hypotenuse layout) track, to the other end of their path, with little excess. While panduit looks neat when installed, it tends to promote over-long wires and is not such a good idea in the final analysis.

Second Edit: We do not have any special software for schematics; we make do with MS Power Point and similar drawing tools.