I am an old graduate (17 y/o graduation), 2 children, took me some time but finally matched this cycle. The way I see it, this is my analysis of the different components that a program looks for (I was the dean of 2 medical schools, so i have experience recruiting candidates):
STEP 1 SCORE: Most important screening factor, if you have a good score you pass first filters (computer and human), if you fail, take it again and pass it with a good score, still score on step 1 is more important than the failed attempt, if you take it a second or a 3d time, take it again until you get a very good score. If you pass with a low score, not a killer, but know that you will lose exposure because you will be filtered out.
STEP 2 SCORE: Over 220 is safe, as step 1, a good score gives you piece of mind. this is not the first score they look at to filter you in. For those starting the process, take step 1 first and devote all your energy and time to step 1.
STEP 3 SCORE: Helps if you have low step 1 score or failed attempts, not mandatory to have. It helps if you have other alerts in your resume.
YEARS OUT OF MEDICAL SCHOOL: Most programs are looking for people with less than 5 years out of medical school. This is one of those factors you can´t change, so again, the sooner you apply the better.
FAILED ATTEMPTS: you can still make it with failed attempts. In the order of how much a failed attempt will affect you I see it this way: Failed attempt step 1 > CS > CK
CLERKSHIPS: This is HANDS ON EXPERIENCE, very valuable, done thanks to agreements between medical schools with american grades. Very recommended. Gives you both exposure, hands on practice and knowledge of the system and EMRs.
OBSERVERSHIPS: Choose your sites. Do observerships in places that could be potential sites to do residency. Some observerships are offered in top of the line programs that would never take you if you have low scores no matter how much they loved you. This is not hands on experience but is better than nothing.
WORKING IN THE US: If it is clinical practice (assistant to a physician, it really helps, highlight patient management and EMR management), if it is public health, research or epidemiology also helps a lot. they want people that have been exposed to the american health system.
PUBLICATIONS AND RESEARCH: it depends on what program you are applying.
STRATEGY: be strategic. This process is expensive and you don´t want to waste your money. Look for the lists of programs that can be friendly to YOUR individual profile and characteristics.
CONTACTS: help a lot! if you pass the first filters, contacts can take you the furthest. I have a very good CV but my application was filterd out for many programs. A phone call to someone in a program can make a difference between getting your file out of the trash and putting in on the table just because the computer filtered it out.
Good luck to all and keep swimming!