best direction to defecate north or south

place of defecation should be a deserted place at least 100 feet away in east, south or north direction of house.

One should conceal head with cloth, 

face north in daytime or south in night time.

one should not defecate in front of Agni, woman, brahmana, Guru and cow and in water, ditches of animals, peaks of hills, temple premises, banks of river, under a tree, areas of food grains and facing temple. 

If urine and stools come into contact with any part of the body, that part should be cleaned with soil. Cleaning should be done first for stools, then urine, followed by left hand, both hands and feet.

ref: https://www.kamakoti.org/kamakoti/articles/Veda%20Dharma%20Shastra%20Paripalana%20Sabha%20Morning%20Routine.html