I have wired up a couple of studios in the last 30 years, the tools available today are so much better!
Try to steer clear of plastic zip-ties. First, they are a pain to remove should you need to add or remove or re-route a cable. Second, if you cinch them to tightly they can, over time damage cables. There are dozens of options for velcro-like cable ties, I strongly recommend them. If you already have bags of the plastic zip ties, and you don't want to spend extra then leave them a little bit loose, that makes them easier to remove and reduces the opportunity to do damage.
Use "cable sock" to group cables together - it keeps things organized, and it looks so much better! In the past I used the spiral wrap and split type plastic tubing, and they work, but I think cable sock works better and looks better.
It is a good idea to group cables with similar signals - either level or type. Sometimes that can be a bit of a challenge, e.g. I generally have only two cables carrying SMPTE Time Code, a nasty signal that seems to bleed into anything else. I finally resolved that one by getting an MTC converter and running timecode over MIDI.
Power - if you don't have 60 Hz noise then count your blessings, if you do then purchase power cables that twist the two power conductors, Middle Atlantic sells them, I'm sure others do as well. Also, keep them short, again you can buy them in specific lengths. Crossing power and signal cables at right angles is still an excellent practice too.
Unless your desk/table is marble or glass it does make sense to create pathways from top to bottom. If you drill holes you can make them look nicer by adding grommets or sleeves, both of which are available from many sources. Since I never know what I want to do next year I generally run cables over the back of the work surface, grouped by signal type, bundled with cable sock, and arranged to minimize crosstalk. It also looks a little nicer<G>. There are companies that sell plastic blocks to hold the cables in place, I've used them in the past, but I have a bin full of cable tie anchors, so that's what I use these days, and I make the cable tie loops loose.
Cabling inside a rack follows all the same guidelines, except I add cable supports where I can. Velcro is the better choice for cable ties in the rack too. Run power down one side, audio down the other, and if you have microphone and line level audio separate them by 6 inches or more. Speaker level audio is not often the victim of crosstalk (except for SMPTE Time code) but it can be the aggressor. I run speaker lines out from the bottom, perpendicular to the rear face, and locate them to one side or the middle depending on the rest of the cables.
Take your time, plan, measure twice & cut once, etc. You can make it look nice with very little effort and not a lot of cash.