In other words, your most successful approach is to create your list in order of your real preferences. Although the Match algorithm is mathematically quite complicated, because the process always begins with an attempt to match an applicant to the program most preferred on the applicant's list, you do not want to try to "game" the system. For example, I've had applicants tell me that they plan to rank a less preferred institution higher because that program has more residency slots. That's a no-no. The applicant will actually be harming him/herself with that strategy.
Here's a video the NRMP created last year to better explain the Match algorithm. Here's also a less-than-one-minute Guru on the Go© video "NRMP Ranking to Avoid a Spanking" to emphasize your optimal strategy.