If you do decide to make the first trip into the backcountry keep the hiking distance short. Little legs are going to have a hard time going more than three to five miles in a day. Curious eyes and hands will want to stop and check out every plant, bug, and rock along the way. Let your child set the pace and decide on rest breaks. If in the end you won't reach your destination be prepared to turn around and go back. Flexibility is the second key to having a successful experience.
If you go car camping or into the backcountry make sure your children have the right gear. A temperature appropriate sleeping bag that is child sized, rain gear, warm clothing if needed, hat, gloves, and comfortable shoes or boots will help your child have a better time. If your child wants to take a pillow or favorite stuffed animal from home let them, lightweight camping can be taught when they are older. As the parent you need to be over prepared. Even if the forecast is calling for sun be ready for rain. Expected to be warm, be ready for cold. You can deal with being cold and wet at 4:00 AM, your child won't, and they will be sure to let you know about it.
Even if biology wasn't your strongest subject in school try to learn a little about the plants and animals in the area where you will be camping. By pointing out really cool features while camping you will increase your chances of being labeled super parent. The unusual flowers of the lady slipper, the tiny princess pine, prickly pear cactus, hairy goats beard lichens, chewing on natural wintergreen, and looking at the massive leaves of devil's club will wow your children. Small insects like ferocious lion ants, dainty water gliders and of course butterflies are sure to entertain.
The third key to success on that first trip is taking a close friend of your children with you. Even though you may want this to be bonding time with your children, the comfort of having a friend with them can help make the rougher edges of camping a little smoother. Even better try to have their parents go with you. We all love our children dearly, but after three days of having the entire world of Pokemon explained to you the desire for a more mature conversation may override your patience.
In the end your child may simply decide that they don't like camping. For some of us that may even be a welcomed relief. The right of passage now complete, you can return that borrowed camping gear. If you love the outdoors you may need to accept that sleeping on the ground with mom or dad just isn't their thing. This leads to the last key to success, realizing that your children can make up their own minds, and letting them do it.