There are several main pieces of information that most applications seek: undergraduate (and graduate, if applicable) records, GRE scores, letters of reference and personal statement. At this stage, I presume there is not much opportunity to change your undergraduate record. Tough you should be sure you have a solid background in the basic sciences. If you haven't taken the GRE's, it is worth putting in the necessary time to prepare for them. Letters of recommendation are important, so choose carefully from among your faculty contacts those faculty that know you best, know your potential and seem to be sincerely interested in helping you succeed in your advanced education goals. Finally, the personal statement shows two things: 1) how well you can write and 2) how mature you are in making your decision to pursue a graduate degree. Put a lot of time into preparing the personal statement, and have someone read and edit a draft. Good letters and a strong personal statement hold a substantial amount of weight in acceptance decisions.
RSMAS accepts graduate students into our program based on: 1) meeting our academic standards, 2) linkage with an advisor and 3) identifying a source of guaranteed funding. The candidate must pass item #1 before the files are even shown to potential faculty advisors. That is not to say that a faculty member cannot look at a file or try to help it through the system, but mostly a potential advisor can only act after the first hurdle is passed. Funding is also problematic. RSMAS has several different fellowship opportunities (decided on within-house); theses are highly competitive (i.e. high GPA & GRE scores) and are awarded early in the admission period, so apply early. The lion's share of funding comes from research grants of the faculty, thus it is limited. You can find more information about the faculty and the School by looking at our home page: www.rsmas.miami.edu.
With respect to working in my lab, take the time to read a few of the papers listed on this website. Also, note that not all projects listed are currently open for new students, but the general area of research typically done in my lab are well represented by these examples. The nature of my line of research often requires shiptime and rather expensive equipment. Therefore, most of my students are funded by, and work on, specific research projects I have proposed. As available, I offer these research opportunities to my students with the intent that they will work on the main thrust of the project as part of their dissertation. Usually, the student will also take the research into directions beyond those proposed in the grant application. The net result is that the research being conducted is a collaborative effort between me and the student (and others at times). Consequently, publication is shared, though I always offer first authorship to the student for any portion of the work they write up and utilize in their dissertation.