He need to study carefully and understand all his college requirments for this type of the essay. There should be also a plenty of examples of other well-written works, analyzing them will be really helpful too.There are also two main rules for writing a really good one, just be yourself and start as early as possible. You need to choose a topic which can highlight you but don't write only such things which are interesting for admission officers. Narrow your topic and find a creative approach for
presenting your own personal story but don't make it longer than the suggested amount of words, this will
make an impression from your essay only worse. Keep you grammar, style and vocabulary on a high level, be attentive with formatting (different colleges can have various requiments for it), include nice citations,specific examples and concrete details in the essay. Avoid cliche, anyplagiarism and covering too many topics in one work. Proofreading is an important thing too, it's recommended to make it at least several times.
Good writing tutor can be the best decision in this case, try to look for them in net, there's a great choice. Various students' unions can be very helpful in this case, some of them can help you even for free, there are also professional services
https://coolessay.net/ for improving and editing the essays too.