Get an early start - Yellowstone is such a popular place in summer that parking lots get filled up, especially Old Faithful. Go early in the morning, it's easy to park and less crowded on the trails around the geysers and hot springs.

Stay on the trails and boardwalks - There are no exceptions. The ground underneath the crust may be very hot and kids must understand that they can't wander off to investigate what's in that bubbling pot. And don't throw anything into the pools.

Hikes - Bring lots of water and drinks in your day packs. Insect repellent is also helpful (even in high summer we found the mosquitoes were quite thick in the forest). Wear closed-toed shoes for hikes, have sunscreen and hats.

Changeable weather - Although it's warm during the day in summer, thunderstorms can come up, so have a light jacket. Daily temperatures vary - in July it can be 44 degrees in the morning, but 80 degrees by noon.

Pack a picnic lunch - There's plenty of picnic areas around the park, with picnic tables and glorious scenery. In the morning stock up on picnic supplies (supermarkets or delis). Then at lunchtime you can enjoy lunch by a sparkling stream or lake, instead of driving miles to buy lunch within the park.

Don't feed the animals - The chipmunks know they're cute, and will even pose for you, but don't feed them. At lunch time, chubby marmots will magically appear, but don't share your lunch. Chips and snacks are bad for many of the animals here - feed them people food and they can end up dead.

Don't get too close to the wildlife - Bison herds are an amazing sight, but don't get too close; bison can run fast and charge, are wild and unpredictable, and visitors have been hurt. Use your binoculars instead and stay at a safe distance.