.PART-writing about what you care about and know about.
PART-writing about what you think about most. Worry about it? Write about it!
PART-deciding HOW you're telling it. Are you in the joke or just reporting it.
PART-Attitude!!! (like your subject? don't like it? is it confusing to you? angry about it? let your audience know)
PART-asking yourself so that you can explain to the audience WHY you're telling them about the subject.
PART-knowing how the joke relates to your big picture (story) you're painting.
And of course PART- editing. rewriting and making your topic more clear...to you and the audience.
That's comedy writing ...in PART. ;)