It is not easy to parent during Terrible Twos and Threes or the teen years. Each and every baby and child is a different person, with different needs, even among siblings or identical twins.
There are a lot of resources that you can refer to on parenting strategies to bring up an emotionally resilient child.
Helping children build a strong self-esteem is very important for their happiness and success in many ways. Connecting with your children about their emotional needs and understanding their issues through their eyes will go a long way in reducing conflicts with them.