I need a good PSU cable management guide/videod

I gave my old desktop to one of my brothers (it is a Dell E510). He says it has been overheating lately. I looked inside of it and I noticed that I never bothered to make the wires nice and neat. So I thought it would not be a bad place to start. I made many upgrades for it (GPU, CPU, RAM, PSU).

When I mean messy, I mean really messy. There is not an 2-3 inches of open space when you first look at it.

Anyone have a good PSU cable management guide they would like to share? Maybe a video? I tried finding myself, but had no luck with one that could help me.

Many that I saw, they have the cables hidden behind the motherboard; unfortunately, I do not think I can do this with a Dell E510.