Plans and Thumbnails. This is where the fun stuff starts!
As soon as you know all the info about the brief you will be taking part in you need to come up with a variation of different ideas, plans, and designs.
Concepts take a lot of planning and thought and if you just go with the first thing in your head then you ruin chances of a better one. Never just go with the first one you have or you blow any better ideas you might have straight out of the window.