Brain Based Strategies to Help Children Handle their Emotions....

There  is a good therapist online.  Her website is tinabryson.com.  She has effective strategies for helping children to cope with their emotions.  Here are a few.
Her lesson number 1 is too be emotionally responsive.  Can you find out what is causing the behavior vs. just looking at the behavior.  This is done by validating their feelings and experiences.  Try to see what they are actually experiencing.  This brings the reactivity down and builds the brain connections.  It also helps to build attachment.  This does not mean that you allow uncontrolled behavior.  Reactivity can be toned down by understanding the child and explaining to them that they are out of control and that you need to take the reins, gently, until they can regain control. 
Lesson number 2 is to communicate comfort rather than threat.  The treat detection in the brain is primitive.  When this part of the brain is activated then the frontal region shuts down.  This means that the child or person will react with fight, flight or freeze.  When the voice is raised, fingers are being pointed, the face looks angry, there is limited thinking being done.  One of the tricks is to get down below the child's eye level and acknowledge how they are feeling.  This is very effective, especially if you address the behavior once the child is calm, not when they are escalated.

LENS can help with anxiety.  It helps to keep the brain smooth and stabilized.