There are many ways to connect wires together or to a terminal. Soldering an crimping are the most common. Crimping is easy, fast and effective. Crimping crushes the wire around the connector and ensures a solid electrical connection.
When purchasing ring terminals, be sure to purchase those with heat shrink tubing. The heat shrink tubing will seal the wire, and provide a professional looking waterproof connection.
Ring Terminals with heat shrink https://amzn.to/3BULhMA
Ferrule Crimping Tool Kit https://amzn.to/3EQTwLG
Ancor Marine Grade Duplex Wire https://amzn.to/30bsQ9C
Ancor produces excellent marine grade wire. It is double insulated and fully tinned. I use 12AWG flat duplex wire for all of the 12 Volt DC applications in the van. Please see my video on wire size!