Spaces and indents count the same as letters so get rid of blank spots to maximise your word count.
To help you write this document, take a step back and put yourself in the place of the person who will be reading your essay. That person will be reading your essay along with hundreds of others. Undoubtledly they will be doing some type of rough sort say Excellent, OK, and Bad. They will spend 10-15 seconds per essay to make those initial sorts. The excellent essays will hook the readers attention and pull them in to read more.
You need to re-write your personal statement to capture the readers interest in you in the first 10-15 seconds. Your entire essay needs to be powerfull and concise. This is about you so show passion in your writing. 500 words is a lot if you use the correct words.
Suggestion write a first pass, work on it a bit and put it away for a day or so. Come back to it fresh, keep editing. Also, consult your parents or someone else that writes well. The ideas and passion have to be yours but a good editor can help you tighten up your thoughts. As a reference it took my mid 2+ weeks to get to that final 500 word essay. It kicked ass when she was done.
Best of luck!