Items not to add include meat, bones, fat, cheese, oils, and other materials that might attract pests and slow down the composting process. Ideally you want to add more carbon to the mix. Adding some leaves to the composter every few weeks will keep your pile percolating. If you rake up your leaves in the fall, keep some bags of leaves to add to your composter. Alternatively just rake them off into piles that you can tap into as needed over the next year.
Aeration helps to speed up the composting process.
Ideally, the pile should be turned every few weeks. In a small composter, just try to loosen it up, to let more oxygen into the mix. Remember, composting can be as much or as little work as you want it to be. If your goal is just to get rid of kitchen waste in an environmentally friendly manner, then there is very little work involved. Your pile will turn into soil over time.