I am a little late to this party but I have to agree with the proper crimping and heat shrink (versus solder, twisting, liquid tape) plus one more, I think important suggestion, related to the one response that I caught regarding the moisture point of entry where the heat shrink doesn't quite close up the gap between the spade (or loop), which is a very common problem. What I have done on well over hundreds of connections with no problems (15 years and counting) is to properly crimp, heat shrink, let cool and then spray Boshield T-9 (in an areosol can) in those small openings (hold the connection vertical and let the liquid migrate into the joint for a few seconds). It is a moisture displacement liquid that also leaves a light waxy film on crimp/wire that will last probably as long as I live (after that, who cares). I go one step further on the large battery connections (although no gaps with the heat shrink completely surrounding the lug and wire cover - may be overkill but maybe not - depends on the quality/integrity of the heat shrink) and spray both the lug and wire before crimping, wiping off any excess T-9 that finds its way onto the exterior of the wire or lug with acetone and then heat shrink (easier to wipe off on the large wires). The heat shrink provides the strength and the T-9, the all important moisture displacement.