I do it in a combination of doodles, words and pinterest moodboards.
More important than the actual technicalities of sharing both written and visual concepts, is trying to get a good grasp on what people want out of the shoot.
The customer is trying to sell a product, the model is focused on her best angles, the designer needs to understand the era... so on and so forth - so I think keeping in mind who you are communicating with and adapting to them is extremely important.
I talk just as much about the end goal, as the image itself - because we have to remember that the image is only 1/2 of the story. How and why it was created makes up the other half and I think both can be equally compelling if done right.