Wash it well and Peel the orange using a peeler. This works in case of clementines as they are hard and can be peeled. Try not to peel deep into the white part as it adds to the bitterness . Just the top layer.Dont be too harsh on yourself self if little bit of white pith remains.
In case of using Indian variety oranges, peel them with hands, and using a sharp knife slice and remove the white part of the skin. Juliene the peel or finely chop or grate using a big grater. I juliene it as I can later chop it according the dish i am using it in.
Boil the julienned peel in 2 cups of water 5 mins and strsin it and discard the water. Repeat this step once more. If you like bitterness in the peel then do it only once. This step helps remove the bitterness to a extent and also gives a tiny bit of peace that i have discarded the chemicals away :) ( i know you can say that i have actually helped the chemicals seep in. Uff its never ending)
Once drained take 1 cup water and sugar and the boiled peel in a wide pan and simmer it over low flame for 20 to 30 mins or till the time the sugar gets syrupy and evaporated completely. The peel will be cooked in it completely and will be bright and transparent.
Once completely dry, rub them between your palm and remove the excess sugar coated on it and store in an air tight container or a bottle in a cool and dry place.. Store the excess sugar for later use. It will have all the flavour of oranges in it. The candied peel can be stored for months if they are air dried well and stored well in dry and dark place.
I use the peel of every orange that I buy. If you are buying only for the purpose of canding the peel then I suggest you to buy clementines.
The more orange the peel, the brighter and orangy and pretty the candy will turn out.
*You can also candy the peels of lemon peel,grape fruit peel or ginger in sinilar manner.