Can't say enough about heat-shrink tubing...

It really makes for a professional looking solder joint. Years and years ago, before I knew about the stuff, I'd wrap a joint in electrical tape. The tape would get dirt and oil on it from my hands, and it wouldn't stick. In weeks, the tape would be unraveling. Just junky in my opinion...

Now with heat shrink tubing. No problems.

One trick I've come to practice... I use two pieces. The first piece is cut to the length of the joint itself. The second piece is much longer. Once I've soldered, I put the short piece on, essentially replacing the wire's original insulation. Then the longer piece seals it all together.