I like adding some yeast, I got the idea from a YouTube video of a guy who puts a soda and a beer in every pile he makes. It speeds up decomposition. I never waste good food though so I either add a yeast sugar and water mix or I add the leftovers from the bottom of my home brew barrel after I have bottled it (it's a kind of wet yeast sludge). It speeds things up and the yeast ferments the sugars in the waste which heats things.