While everyone has a different way to go about creating appropriate concept visualizations, I think these three rules (which I have accumulated through personal experience)are an effective start when a designer begins organizing ideas for presentation.
What idea are you trying to get across in a certain concept. Be concise and arrange your ideation in a meaningful way. A bunch of sketches on a wall don't mean a lot unless it is easy to see a wide range of ideas neatly organized. Extra bonus: it makes it look like a lot more thought went into the work than probably did.
Find a way that works for you. Make this your go to method when you need to get a lot of ideas out fast. When you work in a media and style that is easy for you, there is more time to think and less time spent sketching.
Even though you should work efficiently and concisely, make sure your work is interesting. Creating excitement through visualization is what we are hired to do.