As you juice, you should sample the resulting cider. I juiced a handful of apples, mixed the juice into a big punch bowl, and took a little taste. Then, I'd add more juices from different apples and the citrus until I had the taste I wanted. The cider will change flavors in really nice ways as you craft your blend. I wanted mine full-bodied and very apple-tasting, but tart. The tartness is why the Granny Smith apples were used. The orange juice and lemon juice gave it that lighter, citrus flavor.
I grated in some a fresh clove and then added cinnamon and nutmeg. There was about a teaspoon or two of each, which added a subtle spicy flavor. Experiment!
The spices may clump up a bit, but a wire whisk made short work of them.