Delphi Weather Pack Pro Kit WP-1505 With 2 Crimp Tools: Sealed Weatherproof Automotive Electrical Connectors 20-12 Gauge 1505 Piece Kit With 12014254 and T-18 Crimp Tools https://www.amazon.com/dp/B007QVXT2...abc_63DTW4G6N5B3TQTRKR0J?_encoding=UTF8&psc=1 Buy the kit, then just buy more connectors/pins etc, there are cheaper kits but that one there will last through quite a lot of repairs and gets you the tools to begin with and a good case
Very, very few people know how to properly use crimps. A good crimp requires the proper tool and connector. You will not find the proper tool at a hardware store. (If you are really strict the proper tool is not a universal tool, technically each connector type usually requires its own tool or at least a die set. However, a high quality universal tool appropriate for the connector type usually results in acceptable connections if used with care.) Heat shrink connectors especially have issues because people insist on using the wrong spike type crimp tools on them. This tears up the nice heat shrink insulation, and is often not used with sufficient force to make a good crimp. Combine that with a Bic lighter being used to shrink the insulation over a bunch of dirt, and you get a crappy connection that collects and traps salt and water.
A small 2 truck company I worked for when I was a newb liked to have a ton of chicken lights on the trailers. They had this guy come in and drill holes in the top and bottom rails of the trailers and fill them all with amber lights. Then when he wired them all he just twisted the wires and wrapped them in electrical tape. The things were constantly coming loose and not working. Turns out the "mechanic" who installed them was the brother in law of my boss. Glad I only worked for those morons for a few weeks.
One nice thing about having OCD is I like my wiring repairs and new rig ups to look like they came from factory.
Soldering and using heat shrink is really easy, and anybody can learn to do it like a pro. But if you've never been shown how to do it, it can get messy. The biggest mistake most people make is twisting two wire ends together and then soldering them, but then the heat shrink doesn't fit. When done right, the repaired section should only barely be a little thicker than the wire and insulation before the repair.