Here are a few comments on the work I did and things I learned:
I didn't replace spade connectors on the ends of wires unless there was a mechanical problem with them.
I sprayed DeoxIT D5 deoxidizing cleaner on every connection and then followed up with contact cleaner.
I removed pretty much every old plastic insulator from any wire connections and then reinsulated with heat shrink tubing. This made very nice, neat terminals everywhere.
I removed 100% of the old tape from my harnesses, cleaned wiring as best I could and then retaped with Tesa cloth tape.
I removed my fuse box and soaked it in vinegar as per a post I found on the FAQ site a long time ago. Then I deox'd it and sprayed it down with cleaner. Be careful that the contact cleaner you use doesn't melt plastic! I had carefully marked with wire marker numbers every wire from the fuse box so it went back together well. This is the area that paid off best when replacing plastic connection insulators with heat shrink tubing. So much cleaner and neater now although no one will ever see it!
If you replace female spade (I call them spade but that might not be the correct nomenclature but they are the .250 wide flat tab connectors) connectors you can get the same type as used by BMW from Digikey. Part numbers are A27584CT-ND (18-22AWG), A27587CT-ND (14-18AWG), A27590CT-ND (12-16AWG). The crimper plier I bought is ok but not expensive. It is item 990170 on delcity.net. The crimper has to 'roll' the tabs that grab the bare wire and the insulated portion behind where you stripped the end.
I bought all new headlight wiring harnesses and relays from Daniel Stern lighting. Now that I have it all and having learned a lot I know I could build the harnesses myself for about half the cost but it is still worth it. It's nice quality stuff but requires a lot of new install work. I'll post a photo later of my new 'relay' panel in the engine compartment.
I added a relay operated aux power block with fuses (six new circuits) up under my dash so I could power things later like stereo, etc. This eliminates having to tie into existing wires as had been done ad infinitum in the past by previous owners. All those old wounds in original wires were cleaned and reinsulated with heat shrink by me during the rehab. You can buy a block from many sources but the one I bought was made by Painless Performance Products (part number 70107).
Don't rewrap your harness until you are really sure you have figured out all the new wiring you may want to include! I have gone back and added wires more than once to rewrapped sections of harness. And I am not done with that yet. Hard to foresee everything if it is your first time or if you are designing as you build like I am.
That's about all I can think of for now. I am not finished reinstalling my wiring yet but I think I have learned most of my lessons. I'll post a couple of photos later of what some of my wiring looks like now. I knew nothing about car wiring before I started but it has become a very gratifying part of my total refurb. I know the car will be way more reliable now than it ever could have been without all the time and effort I put into the wiring!