When you think about the data first you can usually synthesize the program. It's almost a game now to try and write a DOOM engine from only the description of the WAD format and its wonderful documentation. I'm under the impression that if you think about your data and how to serialize it first the code will fall out of it.

So I'm starting to think more about formal specifications and documenting serializations formats first and worrying about the code second.

update: punctuation corrections