mix it up well and turn it in spring, putting edges to middle. It is an advantage to have two or more heaps, so that you can turn that one into another bin to finish off, and be using the contents of the third bin while you fill the first. Unless the garden is large, you can mix all the materials, including grass cuttings. They will rot better and faster mixed up.
Leaves contain little nutrient but are good for the soil texture. You can stack them separately, in which case they will be cold and slow to decay.
It is more usual to have a separate muck heap, it will heat up and rot quickly. It's ready when dry, dark brown or black, and crumbly with no offensive odour. Do not leave it so long that it goes grey in the middle. If you have plenty you can then mulch thickly with it, and the worms will dig it in for you. Strawy muck is smelly; woodshavings muck is not.