Having just went through the interview circuit and about to enter the match, I can offer my thoughts on things that I felt to be important.
I firmly believe that the combination of 3rd year grades and the comments from attending physicians on the Dean's Letter are just as important as your Step 1 score. Why? For two reasons:
1. Just about everyone applying into RadOnc is going to have a great Step 1 score. Therefore, the third year grades, IMHO, are more likely to show the combination of character and work ethic that residency program directors seek. A lot of people can bust a** for five weeks and rock Step 1. It takes a whole lot more effort to bust a** for 48 weeks and Honor all of your clerkships.
2. While grades are important, the comments from the attendings are just as important because they can ascribe to you certain characteristics: enthusiam, great work ethic, compassion, empathy, affability. If you really shine on the wards, some attendings may make comments like, "Stanley is one of the best medical students that I have ever worked with and is at the top percentile in all areas." Remember, these programs have to ask themselves, "Do I want to work with this individual in clinic, side by side, for three months at a time?" Personality means a lot in this field because it is inherently assumed that all applicants are intelligent.
As far as scheduling advice:
1. Schedule Internal Medicine last: Step 2 is ~50-60% medicine and so if you finish with medicine you can then take ~3 weeks to study all of the other subjects. Provided that you have studied hard all year long and scored >75% percentile on all of your shelf exams, this should enable you to do extremely well on Step 2. A strong Step 2 score will only re-inforce a strong Step 1 score.
2. Schedule Surgery first: I knew that I didn't want to do surgery, so to get the most difficult/grueling clerkship done first was a great feeling.
3. If you are at all unsure about whether or not you love RadOnc, schedule an elective in the second half of 3rd year. I realize that some schools don't let you do this, but if your school does take advantage of it. You may like the IDEA and LIFESTYLE of RadOnc, but not really like the underlying medicine/principles/day-to-day/planning, etc. It's much better to find out if you like/dislike something in 3rd year as it will make scheduling 4th year infinitely easier.
Assuming that I match (with 10 interviews, I sure hope I do!) I fell like I am about to win the lottery and am incredibly blessed to be entering what I feel is the best field in all of medicine.
Best of luck,
Stanley