I would only solder SS or galvanized cable. The coated cables are going to just not like heat and solder.

Cut the cable cleanly, use a decent soldering iron (I used to use a 100 watt iron but that's overkill), rosin core solder works well. A little flux helps it wick in but isn't necessary. Heat the last 1/8 to 1/4 inch of the cable and apply the solder to the cable not the iron.

Soldered ends look clean and professional, but I like the little aluminum caps on my old bikes because they look original.