I've got time (and energy, very important, lol) as a fourth year now to answer this. This is a haphazard guide I slapped together. I aim to disappoint
LORs
You want to ask for like double the amount of LORs required for your specialty (usually 3) because people are just flakes or do last minute nonsense (I was unfortunate to experience both lol).
Sub-is/Aways
Number of sub-is depends on specialty and your goals (ending up at a specific program or region).
PS
I'd recommend working on your personal statement as soon as you settle on a specialty. Just word vomit whenever you feel inspired by a patient interaction or the subject matter, etc. Keep doing that until you have enough for a page or so, then edit it into a coherent narrative. Make sure to include your why this specialty and real life examples to support it.
ERAS
ERAS apps are actually pretty straightforward for the most part. There are some glaringly stupid things like your photo not uploading automatically, but you can mitigate that stuff by being thorough and triple checking your stuff.
For the hobbies section, people really love "unique" stuff, as dumb as that sounds. Whatever. I'm guessing it's one little thing that separates applicants. Regardless, most of us are not expert windgliders or whatever, so you want to describe your hobbies in an engaging way. They say be specific, so if you like cooking, talk exactly about what kind of cuisine you enjoy cooking. Let your "passion" show through if possible.
Program Elimination
I eliminated a ton of programs just based on cost of living. I'm not willing to be stressed financially on top of being stressed as a resident. I also did my due diligence with the name and shame threads of course, those programs were gone off my list immediately.
Signaling
Signaling is a new thing this year for a lot of specialties; people have had varying levels of success with program and regional signaling. Programs and applicants are still trying to figure this thing out.
LOIs
People get into intense debate over sending LOIs. I didn't send any. Not sending a love letter either
Interviews
For interviews, it's smart to get in a mock interview at some point, especially if you're not confident in your interviewing skills. Some questions that are extremely important to prepare for: why this specialty and why this program.
Your Rank List
For ranking, it's vibes and lifestyle all the way. I just went based on what I felt observing everyone on pre-interview socials and on interview days, along with call schedule, of course.
Electives
Make sure to load up with the chillest electives possible after sub-is/aways. Gas, DR, path, research. I'm sure I'm forgetting some.
Missing Days for Interviews
Whatever you do, don't tell admin. Admin is there to follow braindead rules and they are fundamentally at odds with your enlightened self-interest, actually matching. Just tell your immediate senior and there should be no problems.
Any questions for me? Even if you don't, you actually do. Get used to this