Make sure they know you love them and are proud of them. Even when things are busy or stressful, and it feels like you are in survival mode, a word or a hug can reassure them a huge amount. Praise them for what they do well, and encourage them to try new things.
Be honest about your feelings - you don’t have to be perfect. We all get things wrong and shout or say unkind things from time to time. If this happens, say sorry to your child afterwards and explain why it happened, They will learn from you that it’s OK to make mistakes and that it doesn’t make you a bad person.
Be clear about what is and isn’t acceptable - and tell them why. Children need to know what is OK and what isn’t, and what will happen if they cross the line. Follow through on what you say as otherwise they may get confused or stop respecting the boundaries.
Own your own role - you are the parent, so don’t be afraid to take tough decisions. If your child sees you are scared of their reaction and always give in to them, it can make them feel very powerful, which can be frightening. Children need to know that you are there to keep them safe.