Once it starts to decline, start taking the stuff on the outside of your mound and throw it onto the center top. Once the pile no longer can reach those temperatures, but stays at a moderate temp. This process can take anywhere from 2 weeks to 2 months depending on your involvement in it. This method is perfect for balancing the pH levels as well as killing all your weed seeds and a wonderful recycling method. What you really need to know is that a compost pile is made up of 2 basic ingredients - carbon and nitrogen.
Carbon takes a long time to break down.
Ideally you should have a mix. People will tell you to layer it, but I just throw it on the pile as I have it. It will break down faster if you go out there with a fork every now and again and turn it over. And if you live in a cold winter area and your leaves aren't completely composted by spring, use them as mulch around your plants and dig them in later. I recently started composting my scraps directly into my garden.