My own setup is relatively simple in concept – use a series of spinning concentric circles to alert me to certain powerful spells becoming available. I didn’t want to track every buff or action, but I did want to give myself some kind of visual prompt to take immediate action.
Shadowburn, for instance, is an extremely powerful execute spell that Destro locks should use whenever it’s available, which is when the target is below 20% health and you have a Burning Ember to spend. The problem with the default UI is that the button doesn’t light up when you can cast it (unlike Execute or other similar spells) – it just becomes quietly castable. Adding an Aura to let me know that it’s up allows me to cast it more often. (via Simple Destruction Warlock Weak Auras | Cynwise’s Warcraft Manual)