Ha, this is a question close to my heart. I've been spending MONTHS doing this recently, especially with the weather as it is.
Measure your required cable length first. Then build in the required slack.
Once done, start shopping.
For data cables, I use a combination of Lindy.com.au and Amazon (brands Fasgear and Ugreen... excellent quality stuff!).
For power, well I'm in the process of doing this now, but you can get them from ebay, or find a company that will create custom length cables. I'm going to use these guys:
https://goodwoodaudio.com/products/d...cable-designer
Also think about straight vs right angled vs upside down connectors. They can make a big difference and take stress off the ports in some scenarios.