Several years ago, there was an excellent article in Hot Rod Magazine concerning the addition of relays to the headlight circuits of older automobiles. As my 1986 VW Cabriolet had the dreaded nighttime "yellow eyes", I was interested. Particularly so as I had recently installed new headlights and they were still
yeller.
Part of the rehab was using quality electrical terminals and soldering the wire to the terminal after a proper crimp. This yields an electrical connection that will deliver maximum current and be practically corrosion resistant.
The big deal is locating pre-tinned
copper terminals. Most of what is available are an unknown metal, not copper. Test one by using a pair of nippers or side cutting pliers and see if the base metal is copper or something
not copper.
The drill is to pre-solder the end of the wire, insert it into the pre-tinned copper terminal, crimp. then solder the junction.
Here's a link to the outfit that got me brightened up and driving a bit safer. Mark runs a one-man-band operation up Northern California way. He knows his stuff.
http://madelectrical.com/I bought a boat load of terminals from MadElectrical but there always seems to be a shortage in the toolbox of just what I want. Enter WallyWorld to the rescue...
I recently bought a package of assorted terminals at WM. They are manufactured in the USA and sold under the 3M brand. In the shop, I clipped one of the terminals and, AhHa... pre-tinned copper!
I use a heat sink to keep the wire insulation from melting. A bit of shrink tubing tidies up the whole package. I find that they are well worth the slightly higher price of the Taiwan/Chinese terminals offered for less money.
Give these terminals a try when you're doing electrical hookups. You will not be disappointed.

These little rascals are
the bomb when used as a heat sink. Just can't remember where I got 'em.