What’s your favorite cleaning method for connections

Deficit

Isopropanol.

Cheap, mildly toxic rocket fuel. I have used everything over time and this works the best. Drop some onto toilet paper, clean and then breath on and dry with another wedge of the same. Do not use with wet fingers.

Clean well with deoxIT then spray on preservIT. Pretty much the industry standard for recording studios & audio gear. Supposedly cleans & improves conductivity. I use it on my tube pins as well. 

This costs a little less than Deoxit. Make sure when using contact cleaner that it is also a lubricant, 

https://www.amazon.com/CRC-Contact-Cleaner-Protectant-Aerosol/dp/B007I9Y200/ref=sr_1_42?sr=8-42

Being a pro Bass player has taught me that the best instrument jack cleaner is a product called Flitz cleaner.

Applying it with a Q-tip and polishing it with a fiber cloth removes all built-up corrosion and oxidation.

I now use it on all of my banana plugs, spades, and even battery tips.