There are no universal essentials for happiness. Everyone has different stuff that makes them happy.
However here are some that might apply to many:
be content with your life. Do not use others as a measure of how your life is. Everyone has a different path in life.
Do not make material stuff be the source of your happiness. Learn to grow happiness from within. Be a happy factory.
Do not dwell too much on the mistakes of the past and do not concetrate too much on the future that you forget to live in today.
Forgive those who wrong you.