For old enamelled wire, of the sort you can't solder through, do the following. Get a small metal bottle cap, half fill it with methylated spirit or isopropyl alcohol, and light it. Heat the wire to red heat in the flame, and quench it in the alcohol. Remove the wire quickly, don't allow the flame to heat it again. You'll be astonished. If you've done it right the end of the wire will be bright pink copper. It will solder beautifully. You have to be more careful with thinner wires, as they melt too easily. Get a few metres and practice!