Illustrious 18. A term coined by Don Schlesinger to describe the 18 most advantageous deviations from basic strategy, based on the Hi-Lo count. The 18 plays described equal about 80% of the gain that could be had from playing the full set of indexes in more complex strategy tables.
Fab Four. A term coined by Don Schlesinger used to describe the top four surrender plays that vary from basic strategy based upon the hi-lo counting system.
Basically, learn these 22 indices for your count, and you are playing pretty well.