I can say the earlier you know you're wanting to do a surgical subspecialty, the better!! If you're an M1, really focus hard on making the grades and studying hard for the step 1 that will get you AOA and open doors for your interviews (several programs have cut-offs of 240, 245, or 250). You can try and do some research, but your involvement as an M1 is probably pretty superficial. The key to research is that it allows you to get to know people in the program and gives you something to talk about in your interview. Really academic types only want to talk about research so if you have some (even if, like me, you only have one project, but you know it really well and it's kinda cool and you can talk about it with the best of them) it goes a long way to them liking you on the interview. Also, you don't want any blank spots on your CV. And, it can be in anything! Basic science, urology, ortho, etc!! Academic chairs know all the other academic chairs so if you can do research with someone and get a letter from them, all their friends are going to call and ask about you.
One of the major things you can do is extra-curriculars. My med school had a lot of intra-mural sports you could participate in and that gives you something to talk about because you'll find that a lot of faculty are very successful at whatever they do and they respect that about you if you are (doesn't even matter if you like the same things...if you're passionate about it and you worked really hard to do well in curling, they can appreciate that even if they've never even heard of the sport!!)
Aways - must do!! 1 or 2. I don't know anyone who matched with me who didn't do an away rotation. I just gives other programs an objective view of you from people who don't really have a vested interest in you. Also, it increases your chances of matching at those programs. WORK HARD on those rotations. You'll never work that hard again (even as an intern!) so make it worth it! Be the first to arrive, be the last to leave, don't take a day off...it's 4 wks of hell for your future. You can do it!! It'll also be 4 of the best weeks of your life.
Long story short, things to focus on:
M1 - grades, extracurriculars, go on a mission trip, figure out if you want to do surgery....
M2 - grades/step 1
M3 - rotations (A's in most especially surgery), some research, start gathering letters of recs (only from plastic surgeons...they don't want them from anyone else. Academic better than PP)
M4 - Away rotations - must do 1, better to do 2. 3 is overkill...kind of looks desperate! Take step 2 early if you didn't do so hot on step 1. Otherwise, put it off till spring. Take Dec/Jan completely off for interviews. Go on as many as you can...you'll be surprised at the programs you really like (like Mizzou--not the program I'm at, but I really liked it which surprised me!!) or don't like...
Hope this helps some people out. It seems overwhelming and it is an impossible process, but just take it one step at a time and it'll all work out! I didn't end up at the place I imagined (didn't think I had a shot at getting in here) but it all worked out in the end.