Where do you start?

Following on from yesterday's post about getting back into writing, I watched Get Carter again last night and felt even more inspired to put pen to paper.
I always find writing anything competition-based gets me completely bogged down with too many questions... What are the judges looking for? Will Judge X like this because it's similar to their work? Are they looking for a commercial idea? Will something with limited readership appeal still have a chance if the writing is good? The list is endless. The answers? I'd imagine it is a bit of everything. I don't think it is worth entering any writing competition if you are catering to the tastes of the judges, but all judgements are based (to an extent) on personal taste, whether we admit it or not. A commercial idea is obviously something that will make the competition look good if it has mass appeal and goes on to become the next Harry Potter - but critical acclaim is always what we seek as writers too.
On the subject of ideas, what about high concept? Here's another blog with an interesting post on high concept worth reading.
And now you're bogged down too.
My apologies.

There are books on how to come up with ideas, books on how to write books, books on how to write short stories and probably even books on how to write books on how to write books.

What do you do then? It's simple - writers write. Get writing! Revisit that novel with a fresh and optimistic 2008 eye. Don't get bogged down by thinking all the what ifs, just write your story, get it out, don’t procrastinate. You never know when these competitions are going to be announced, so don’t get caught out by having a high concept one-liner and 300 blank pages.

Stu