a professor at a leading US university, I have some advice for those of you who are applying to doctoral programs at top 50 B-schools (NOT for other programs). 
Some important tips:  Generally, you cannot make any mistake. One bad recommendation can kill you. This is important to those of you who are studying in US: if you only know an American professor for a few days, DO NOT ask him/her to write a recommendation! -- even if you think you have really impressed him/her. 
Secondly, you must have something that stands out. Usually doctoral programs only admit fewer than a handful of students a year. Every faculty member is asked to pick their one or two top choices and only those candidates are discussed at the faculty meeting. So you must be top on someone's list, otherwise even if you are generally strong, you may not even be included in the picture! 
Third, contact faculty members. If you are in US, visit local schools and call schools (of course visit is better if you can afford it) in other cities. Even if you are in China, emails and calls are always important. About components in your file: GMAT: at least 700 to be considered; there are exceptions, but that's VERY VERY rare, almost inapplicable to any Chinese students. I'm talking about NOW, not a few years back. Now competition is very keen. GRE is okay, though not that comparable. 
If you use GRE, every part should be 90% higher. Again, GMAT is important. And a GMAT of >750 can be the one thing that makes you stand out. Education & experience: A master's degree, or Work experience after you got Bachelor's, is helpful. Where you get your bachelor's matters a lot. Undergraduate GPA is not critical, but if too low, it can still kill you. Years of relevant experience are a big plus.  Research experience or publications: not everyone has it and if you do, it is certainly a big plus. 
By publication I mean publications in English, especially in journals. But don't worry if you don’t have any. 
Statement: As you all know, it is very important. Some Chinese students make the mistake of writing like a Chinese high school student. Some sentences seem really weird in the eyes of American professors and they ask "what is he/she going to say" -- though of course I understand it comes from some bad habits formed in high school. A moving statement can be really impressive, -- one applicant from India won everyone in my department simply by her statement -- but that is very rare. And I suggest you don't try it. Play it safe and write in plain English. Most American applicants write in very plain style and that's okay! It seems that Chinese and Indian students like to "write articles" maybe because of cultural reasons. But Indian students had their education in English and have their advantage. 
More about statement: 
1.The only thing matters in the statement is that: you should make it clear that you love research and you are capable of doing research! Anything you say should supp