Lay out your goals
As a high-achieving student, you're probably quite good at setting (and achieving) your goals. Consciously laying out your goals will help you sharpen your admission strategy.
What's your pitch?
When targeting your readers, you'll need to convey your idea and distinguish yourself. Another way to think about this is that you'll need to sell yourself to the admissions committee. And, as in a marketing campaign, you'll need a pitch.
In practical terms this means being conscious and purposeful about the message you are sending to your reader. How would you like your readers to see you? An energetic achiever? A thoughtful scholar? A passionate leader?
Have ONE message
One of the biggest mistakes people make when promoting themselves is to try to be everything to everyone. Having five messages is like having no message at all.
You don't have to be perfect
When crafting your message, avoid portraying yourself as an infallible demi-god. Most people, admissions officers included, don't like arrogance. Honesty is probably the most important quality you'll be trying to convey.
Indeed, writing about one of your flaws is far more interesting than bragging about your accomplishments. What's more, it demonstrates the kind of maturity and self-awareness that is highly desireable in university students.
Coordinate your strategy
When possible, tell your recommenders about your strategy. Let them know how you want to portray yourself. Some recommenders will have a very strong sense of what they want to say about you. Others may not, and telling them what you plan on writing about yourself can help them craft a complementing message that reinforces your own writing.