Ask HN: How to develop the creative side of brain?

I can recommend a great book: Serious Creativity by Edward De Bono.

I am very interested in this topic and this is the best book I've ever read about it.

“Just think about it deeply, then forget it…then an idea will jump up in your face." - Mad Men.

Play with Lego bricks, doodle, fly a kite, stare at clouds, let your inner child out.