Nowadays, every room has a standard of an eight-foot ceiling. In case of that, for better airflow, keep your fan at least seven feet from the floor.
For rooms with heights over 9 to 10 feet, it is important to maintain the air circulation, as higher the fan lesser the air will circulate near the floor. In such cases, use a down rod and hang your fan from there.
In case of the sloped ceiling, select the right mounting kit for the fan and mount it close to eight inches from the ceiling.