What is a story?

Look at strengths that you want to "display" (i.e. leadership, community involvment, initiative, ability to adapt to unfamiliar terriroty, etc)...then look at all the antecdotes in your life, and pick the situations that best demonstrate said attributes. That's your story.

Just my 2 cents, and perhaps I'll get flamed for saying this, but I would hesitate to mentioned sexual orientation as part of your story. I don't see how one's sexual orientation is a basis for one falling under the diversity tree, and trying to spin it as such may really back-fire. I would only mention it if you participated in a reputable community organization for LGBT and your involvement illustrates key leadership attributes.

But then again, you may not want to listen to me - I am after all reappying this year

the best advice i've received on telling a story is "don't wave any flags". i.e. - if your essay turns into a sobfest about being X (poor, gay, minority, etc.), then you probably won't get in. however, if you can write a good essay and maybe throw in a sentence or two about how the fact that you're X (poor, gay, minority) helped or hindered you, then your essay and story will be better.