How do you layer children clothes in the winter

How do you layer children clothes in the winter? They get hot start sweating it's bad to be wet and outside in the cold weather so I'm not sure how to dress I prefer a coat but I'm not running around at a park the children are so is a sweater good enough but what if they sweat is a regular long sleeve okay. I'm worried because it's a thing to wear a coat during the winter hat gloves so it's usually 34 degrees Fahrenheit to 50 degrees Fahrenheit this is the weather I'm working with and how long is it okay to be outside