Choose a generous sized pot. Use Ericaceous compost, same as for heathers and azalias. Add some water retaining crystals if you might be away on occasions. Place in part shade. Not east facing. Keep well watered and fed with an ericaceous feed, especially July-Sept to allow plant to form buds for next seasons blooms. Camellias are potentially large shrubs, and would really like to be in the ground. They need a bit of fussing in pots if you want to get value for money.