Research experiences and publications are good to have and are good talking points during interviews, but their importance varies significantly by program and specialty. Also, if you have a chance to do oral/poster presentations at US based conferences then go for it. This is what many programs pride themselves on when it comes to their residents' research involvement, so when they see that you as a student were involved in such activities it is a bonus.
In my opinion, the best formula for the match is good scores and a well-rounded specialty-focused application, including clinical electives (in your specialty of interest) at a mix between top name institutions and IMG-friendly reasonable programs (you can figure this out through looking at the residents’ profiles on the program’s website). The easiest way to match is to have a strong connection from within (which may be achieved during electives, research or through family members), but even then, you will need a good application. If you are rotating in a program, express your interest to the right people. Ask the chief residents who the members of the committee selecting residents are and try to meet them.
Every person matching has a unique story that is probably difficult to replicate, but these are some general observations.