My advice for cooking with kids is simple. Take a deep breath and plunge in.
Step one is hygiene. Teach kids about washing hands, washing the tops of cans, not licking the spoon and bowl until they are done, and using separate cutting boards for veggies and meat.
Step two is to start them young. Young children (two or three) can wash fruit, sort fruit, stir a bowl of food, wash cans, hold the cookbook and many other things that don't involve the stove or dangerous appliances.
Step three is to get a few step-by-step, kid-friendly cookbooks. There are dozens of them and most libraries have a great variety. Let older children look through the books and choose a recipe. Then let them plan a shopping trip and get the ingredients that they need. Don't worry if it is something that you think is a bit hard or they may not like. Kids will often eat things that they made themselves, even though they wouldn't eat it if you had made it.
Step four is to dig in and get messy. Cooking is fun and messy. Don't worry so much about the mess. It is a learning process and, in time, the messes will be less. Besides, most food spills clean up pretty easily.
Step five is to introduce the more dangerous parts of cooking. Once kids are good listeners and have some self control, they are ready for mixers, using the stove top and knives. We have not had a major injury yet. The kids have gotten a tiny burn here and there but nothing that some cold water couldn't fix. In the beginning (maybe for years), you will be working right next to them and making sure that they are working safely.
Then all of a sudden, like magic, they will be able to cook! They will be able to plan and make meals. You can sit back and watch from afar while they put a complete meal on the table.
The final step is to teach them to clean up after themselves. It may not be the best part of cooking, but it is a very necessary part. You will be much happier letting them into the kitchen next time, too.
My kids love to cook. They are passionate about all parts of cooking. My youngest son loves to decorate the table and make up his own recipes. A few times a month, I try to let him be really creative (within reason). We have this ongoing discussion about the importance of learning which ingredients go together. We just don't agree on how to learn which ingredients go together. He thinks he should be allowed to create to his heart's content until he makes something edible. I think he should follow recipes until he understands what flavors work together. We usually meet somewhere in the middle. For instance, tonight he made a salad by washing the greens, mushrooms, and bell peppers. But he wanted to experiment by not cutting them into bite-size pieces. So he placed large hunks of veggies into the bowl. His Grandmother, who was here for dinner, called it a "Do It Yourself Salad," because we had to take the greens, mushrooms, and bell peppers out of the salad bowl and slice them ourselves onto our plates. It is an adventure to let kids cook, but I am so glad I do. Give it a try!