While a person is relieving himself, one should sit down whether it is to excrete or to urinate. One should never urinate whilst standing. Be very careful of the splashes of urine (being unmindful in this regard causes one to be punished in the grave).
Additionally, one should not face the Qiblah or show his back towards the Qiblah. Also, one should not speak in the toilet. After relieving oneself, in order to cleanse, one should use water.