The connector blocks available for general eletronic bay wiring uses #6 18-22 AWG solder terminals for making circuit connections (note: SMT Designs crimp termnals used for bay wiring require a different preparation method).
The steps here will give you a connection that you can rely on for many flights to come. A small pair of vise grip pliers were used to hold the ring on its side, but make sure you just clamp on the edge of the ring and not the whole ring (otherwise the pliers will act as a heat sink and make soldering difficult).
What you need for this
Step 1 - strip 3/16" of insulation off the end of the wire
Step 2 - slide the solder terminal on the end of the wire
Step 3 - use a soldering iron pressed on the ring side of the barrel toward the lower part of the barrel. Feed solder between the barrel edge and the soldering iron and apply enough solder so you see it wick into the barrel. Note: connector expects that the barrel on the outside has no solder accumation on it. Also, keep solder from filling the end of the terminal where the #6 hole is.
This completes preparation of a solder terminal