Wash the collard greens, remove the stems and any bad spots, then chop or shred. Cook the ham pieces slowly in the oil until crisp. Add the water and simmer for about 10 minutes. Remove the ham and set it aside. Add the salt, sugar and collard greens to the pot. Turn the heat to medium-high and bring the water to a boil. Stir, then turn the heat to low. Let the greens cook slowly, adding a little hot water if needed to keep them moist, until they are tender (about 45 minutes). Mash a stem to check for tenderness. Once the collards are tender, you can chop them smaller before serving if desired. Ham may also be added to the greens, if desired.