Would recommend reading this book that has a self explanatory title, note there are many similar ‘How To Talk’ books in this series.
One of the main points when speaking to children is to give them time so they can speak. If the child is speaking then it is a good start.
The book outlines various communication points, with theoretical conversation using two approaches to lead to more rewarding and productive discussions. For example “I want this …” previous response “no is too expensive” now “wouldn’t it be good if you can have that … I would like it as well … shame is too expensive … let’s think what could we do instead.