I use a home made case lube of alcohol and lanolin and spray the cases inside a large zip lock bag. Then just work the cases with your hands spreading the lube. The alcohol evaporates and leaves a thin coat of lube. I use this method when doing large batches of .223/5.56 cases for my AR15 rifles.

For small batches of cases I just use my fingers to spread Hornady Unique case lube.