Working with the fat at as frozen as possible (Its easier to handle this way) chop it into a 1 inch dice or smaller OR slice into strips that will fit in your meat grinder and run it through the meat grinder.
Dump your fat into a pot that fits it all, and add 1/2 cup water to the pot. Turn onto medium low heat
Gently warm your fat, giving it a stir. As soon as the "cracklings" start to turn a greyish brown and all the fat is melted, strain it through a fine mesh strainer
You DO NOT want the cracklings to start sizzling or they will flavour the fat. This is not bad, its just not ideal
Dump the strained fat into a clean pot and warm on medium low heat until no steam comes out. This way you've evaporated the water and it will last longer
Pour fat into containers or jars of choice. I find getting fat out of jars and cleaning them REALLY ANNOYING so I use freezer containers.
Let the fat cool until firm/solid, then put the lids on
Label it and put either in a cool dark place, fridge or if no other place, the freezer.
I've kept it in a cupboard at 15C/60F for a couple years without it going bad, but your climate may be different. I currently store it in my root cellar which is 5C/40F in winter and 12C/55F in summer