Tip 1 and 2
1. Create quick goodbye rituals
Hanging around and trying to calm and sooth your child may only make the situation worse. Come up with a mutually agreed upon gesture that you both do to signify the goodbye. My son and I use the book "The Kissing Hand" for our ritual.
2. Practice being apart
You can't expect your child to be okay the first time you drop them off somewhere if you haven't practised it in a setting they are comfortable with. Use grandparents, friends, neighbours, and other relatives to run through the drop-off routine. Leave your child with them for a short period of time, so they actually see you leave and have to deal with being away from you.