Agreed, soldering ain't great in cars due to vibrations, but pre-insulated crimps are crap. Uninsulated terminals with a ratchet crimping tool are the way forwards
Best tool I ever bought was a coolant hose clamp remover, saves so many hours of fannying about with pliers - now I have the proper tool, I actually prefer the stock VW sprung clips to jubilee clamps! Get one NOW!
Also a low-profile jack, just make sure all the bolts holding it together are always tight

Big hammer is a must (for beating the f**k out of your chassis when things don't fit), as is a section of old exhaust to use as a breaker bar
Mig welder is a brilliant tool for so many things, if you're gonna be playing with old cars for more than a couple of years, get one and teach yourself how to use it

, and an angle grinder too!