Some mark the animal for sacrifice on the right side, others on the left

It is narrated from Hazrat Ibn Abbas (may Allah be pleased with both of them) that the Noble Prophet (peace and blessings be upon him) marked the right hump of the sacrificial camel and smeared blood on it.

Whenever Hazrat Urwah intended to perform the Ish'ar of a camel, he would do the Ish'ar on its right side.

If Ibn Umar (may Allah be pleased with them both) had one camel, he would perform Ish'ar on its left side with his right hand, and if he had two camels, he would perform it on the right side of one camel and on the left side of the other.

Hazrat Saeed bin Jubair would recite poetry on the right side.

Hazrat Qasim would gesture to the right side during Hadi.

Hazrat Mujahid says that you may gesture in whichever direction you wish.