Tips from my personal experience:
-If you haven't started saving up $$$, do so now! This process is terribly expensive.
-Either study for the MCAT over an extremely light semester or take it over the summer but take it EARLY. I took it pretty late which caused me to later send in my secondaries pretty late. Although the consequences of applying late are a bit exaggerated here on SDN, you will really be at a better place if you apply early.
-I self studied for the MCAT, which was fine, but if I had the cash I would have taken a class. They put you on a routine schedule and you get access to some pretty awesome materials.
-In studying, focus less on memorizing all the minute details and more on understanding over-arching concepts. You want to "think MCAT". The science sections, from what I've seen, present you with basic concepts hidden behind what appears to be novel topics. If you can identify the basic concept being tested with each question, you will do fine!
-Start on your AMCAS early. Get your transcripts in early! Work on getting your committee letter (if your school has one) early.
-Proofread, proofread, proofread. Then have other people proofread for you. This goes for AMCAS, PS, and secondaries.
-Do some self reflection before applying and try to gauge 1 or 2 'themes' present in your path to medicine. Weave these 'themes' throughout your AMCAS work&activities descriptions and your PS.***This was a huge piece of advice I received from someone else. I've received numerous compliments while on interviews on my AMCAS/PS and I largely think this is why.***
-Research and come up with a realistic list of schools to apply to. Start early because this takes time. For me that started out at 22 schools but ended up being only 16 schools I actually completed secondaries for and I've been fine.
-Be confident on interviews. Don't get intimidated by the superstars you meet on the trail. You are there for a reason!