How to prepare?
Decide which engine/libraries to use. Usually you have your favourite library about, but do you still remember all the little details? Maybe some base code changed and things don't work out of the box anymore?
Set up an empty project that opens up a window and sets up everything. Run it and be ready...
Interested? The competition thread is over here: https://www.gamedev.net/topic/668847-the-week-of-awesome-iii-the-third-annual-unofficial-gamedevnet-competition-administration-thread/