To this point in my career, I've dealt with billing in one of two ways: 1) by the completed minute, which works great for music and full cinematic sound design 2) by the individual sound effect.
With that in mind, I have no idea how to bill for a larger project that will require more than a handful of sounds. Do I count up all the sound effects and bill them by number, or do I take a total time on the effects and bill them that way, or is there a better solution for this?