I wouldn't worry about USMLE scores, but if you didn't do well on Step 1/2, try and do better on 3. My guess at the 2 most important factors are research and training program (although citizenship seems to be a big factor too). Different programs use different screening methods, some might use a cutoff, some just care if you pass (even top programs). I got around 200 on Step 1/2 and 230 on 3, interviewed at Sloan Kettering and MD Anderson, no one brought up my score on interviews except one guy at Moffitt, who said, "You didn't do too great on Step 1/2 but picked it up on 3." An attending at my home program told me you get a point if you passed in the intial screening process, but I don't know if higher scores factor in down the line.