Like wedding photography, you have to get it right on the day, you may not get a second chance.
Organise the shoot.
What is the style of the shoot, traditional, modern, creative, arty, fun or all of them.
Come up with fun ideas that will interest them.
Discus wardrobe do's and don'ts.
Have a plan if the weather is bad, postpone last minute or go undercover somewhere.
Know the area for the shoot. If you don't already know the area you will need to visit beforehand or get there early. What direction will the light be in for the time of the the shoot. What will make a nice background for the style of shoot.
When you meet for the shoot, take some time to talk to them to put them at ease, to get that pose, natural smile or that special look.
During the shoot, give them feedback with encouraging words, that click of the shutter, a smile at the image on the back of the camera (even if it's rubbish) and constantly showing them the pics. Point out what pics you like and why and find out what they think so you can all keep doing the do.
Direct people. Keep things moving with ideas and listen to what they are saying. If you have an idea, say, don't wish you had ofter the shoot. Experiment but be respectful, this is someones little girl.
Create arty pictures even if you don't feel arty at the time.
No pressure then!