[rco8786]

Pen and paper (or whiteboard, if available) has yet to be toppled as the king of design tools, IMHO.

[Phreaker00]

Completely agree that this is the easiest way to do it. Especially a big whiteboard that can hold those sketches to come back to is really valuable. If only it was just as easy to digitise (not looking at you, laggy overpriced smart board).

[GianFabien]

We just take pictures with our smartphones. If it's a really big whiteboard, then do it in overlapping sections.

[baremetal]

second the pen and paper

i diagram everything on paper first.