At the risk of sounding too simp0listic - play lots of word games (boggle / scrabble / upwords). Try making a "story box".
Need to find - empty shoe box. Picture book / non-fiction book that your child really enjoys.
Any materials you can find: wall paper / felt / etc
Contents to enable retelling / expansion of the story.
This can be anything at all - soft toys / lego / hand drawn or photo copied paper characters etc.
Lollipop sticks to attach mini characters made from paper or card.
Read the book together
Talk about the pictures
Invent alternative scenarios!
Make the characters / props
Decorate the indside of the box to representative of the common back ground from the picture book
(Decorate the outside of the box to make it look exciting).Wrapping paper is good
Once the child had explored / discussed and retold the book confidently -
suggest recording it (either tape or video) to share with other family members. Offer lots of support and encouragement.
Use the box on a weekend when the child is not tired from being at school!
Story boxes are confidence building too!