Out-of-box,
1. Imaginary introduction of a future event
I would probably leave this out, but it's conceivable that you could make it work. The problem with this is that it requires you to start
en media res (in the middle of the action), which could cause the adcom to ask "Why is this relevant?" You want to avoid having someone read your essay, get confused, and feel like they need to reread it to contextualize your goals. They won't do that. To me, the safest and most effective way to go is to have your future goals / event be the logical conclusion of what you have done and are currently doing (i.e., your past and present condition that have already been laid out in the beginning sections of the essay). In other words, don't let the caboose drive the train.
2. Starting with a quotation or something someone said to you'
Some people don't like this because they think it's cliche, but it can be highly effective. I used an obscure (and relevant) quote to kick off my goals essay.
3. Anytime in the essay that you deliberately let go of grammar for style.'
Don't do this -- it makes it seem like you don't know grammar. This is a business school essay, not a creative writing class.
4. Humor. ANYWHERE in the goals essay
This could work if you are funny, but it's risky.
5. Description of a personal NON-career event...such as "my parents came to this country with no money..." or "while travelling in nicaragua, i discovered that climbing mountains ...."
I think this adds a lot if it's relevant and not whiny.
content-based-vanilla-but-well-researchedd essay,
1. Starting your essay with "I believe.."
NOOOO!!!!!! They know you believe it or you would not have written it.
1.a. Starting a sentence with "My short-term goals are .."
I recommend this to avoid confusion about what your goals are. It's okay to be very straightforward when guiding the reader to relevant issues.
2. Starting your essay with "Having worked as a..."
No. I'm already bored.
3. Not having ANY personal reference in ANY sentence of your essay. Personal reference means talking about a non-career focus.
It depends on what your career is, but it's reasonable. This can go either way.
4. CRYSTAL CLEAR by paragraph definition of "Past achievements, Short term goal, long term goal, Why MBA? Why now? Why this school?"
These items should be crystal clear no matter what.