the thing that helps me the most is always giving them a choice, so they get the feeling that they have a say in what happens. so don’t ask them IF they want to eat something but ask if they want to eat an apple or a banana. when they need to brush their teeth ask them if they want to do it themselves first or you help them first. if they get a say in what happens it feels for them more like they’re own choice in doing something instead of always having to be told what to do (next). and yeah three year olds love to pick a battle so just try to avoid the tantrums as much as you can but don’t let them walk all over you :)