There really is no measurement guide for this concoction. Just chop up the fruit, one kind or a combination, and place in a med. sized pot. No need to core or peel. Add the spices or herbs. You can use just one spice or herb but I've found that a combination is often wonderful. Add water to cover the fruit. Slowly bring to a simmer and then turn down to low. You can also put it in a small crock pot on high. Look for a med. sized crock pot at thrift stores or yard sales specifically for this use. You can often find them for $3-4 (and they don't need the lid!) Just be sure to place your crock pot where children and pets won't disturb it, especially if it doesn't have a lid!
If you want an especially strong scent you can add essential oils to your potpourri. These can be purchased at many Whole Foods or health food stores. Common oils to choose are: Lavender, Cinnamon, Clove, Eucalyptus, Lemon, Grapefruit and Rose. Experiment and come up with your own signature scent!
Here are some combinations that work well.
-Chopped apple, minced or dry ginger, cinnamon, cloves
-Orange slices, cranberries, and some nutmeg
-Lemon slices, sage leaves, and a bit of basil
-Lavender flowers, sage leaves, lemon zest
-Grapefruit, orange, and lemon slices