Attention: This build is focused around movement speed (i.e. Hec's passive). You should try to use Shurelya's and Youmuu's together whenever possible. If Ghost is up you might save Shurelya's for catching a champ trying to slip away.

Start:
First thing you will do is wolves > blue > wraiths > red. After you are double buffed, gank the closest lane where the other team is pushed (most likely using your ghost with your e for the extra damage and it will keep them from escaping). Once you get good at Hecarim you should get a kill on every first gank. Poor entry or poor execution will lead to them getting away for sure so think about where you are going to enter. After this just gank hard and often while watching your jungle. If there is no gank help push a lane or counter jungle. YOUR WRAITHS AND WOLVES DON'T HAVE TO BE DOWN AT ALL TIMES. Just grab one of them between ganks. Since Hec is so mobile you should never stop moving for long (which really should be true with all jungles).

I would like to give credit to Siv HD for his Hec guide using the movement speed items. His build is where this one came from.