There are a lot of highly-rated books on Amazon that I would personally never recommend. Many of them fall into two categories -
1) self-promotion. They feature a lot of 'contributors' who wanted to their name out there for resume and personal-business' sake. Everything sounds flashy and nice, but the information only gets you so far.
2) common sense-based. They feature advice that isn't exactly wrong, but doesn't help you write amazing statements either. The key word here is 'amazing.'
One reference in particular that I find effective is Harry Bauld's 'On Writing the College Application Essay'. He is/was a full-time English teacher and has admissions experience, so his advice is much more practical and useful for students at the drafting stage. His examples and commentary are spot-on and up-to-date, unlike a certain Harvard reference.
Alternatively, you can check out my online guide. It'll walk you through the whole process - getting into the right mentality, brainstorming, drafting, revising, etc. The App Style - A College Application Guide