For facing creeps you can just tell your hero to attack them and if you are attacking them then you will be facing them.
The easiest way to aim at an enemy hero is to ult them and at the end of the ult you will be facing directly at the enemy hero. Just make sure you start hitting your flurry skill right after your last attack on your ult.
Overall the skill requires timing. You have to know when to click the skill so that you will facing the hero if you are turning. Just practice it a bit and you should do fine.