If the flux capasitor was real I'd go back in time and....

There are a few commonalities in what those applying for grad and preprofessional schools say they wish they would have done differently. Maybe it was their choice in major, many begin college thinking that they had to major in the hard sciences to get into the schools they wanted, when in reality the statics say prove almost the opposite. Schools love diversity and they love excellence so you can major in what ever you want (as long as you still perform well on the prerequisites) as long as you do well.
Another point brought frequently is studying for the mcat early and taking the mcat in the spring. It is one of the biggest tests you'll ever take and cramming the night before will not help you out one iota.
Start filling out the application in the winder and spring. (you don't have to send it out until you're ready) Its not going to get filled out over night or even in a whole week. If you want it to come through perfectly write personal statements and rewrite them, email them to friends and family, get an English professor to look over it, use everyone in your circle of influence to write it.
Sign up to interfolio, it costs about 20 dollars per year but this is a great deal considering how difficult it is to collect letters of recommendation. (a side suggestion, ask your writers if they could honestly write a good letter about you early on and be persistent in reminding them to do it) You can then easily have them write a letter and mail it to interfolio where its archived or they can send it electronically. Get lots of letters, we don't have a premedical committee so you will need at a minimum 3 science professors and one non science professor. Secondaries might ask for people you shadowed or worked for, or served with. So its not a bad idea to get these ahead of time preferably before too much time goes by and your writers forget details about you.
So a quick recap major in something you love, where you genuinely have interest. Plan your schedule so you can succeed. You cannot spend too much time preparing for the mcat so start early. The application can be filled out without paying anything or having to turn in anything so take a look at it, begin filling out the information, at least start figuring out what you need to work on and getting organized. Get good letters of recommendation, use a service like interfolio to store them for when you're ready to send them out.
And lastly be sure that you're going into medicine for the right reasons; money, and prestige, approval of parents for example are not good reasons to go into debt and work insane hours doing something that is hard. admissions officers can see right through you if there is no genuine desire to follow a career in the health care industry and they can spot the delusionals who have this pipe dream of making six figures and having people worship you as an authority figure. There are easier more secure ways which require a lot less sacrifice to make tons of money, and if that's what will make you happy medicine is probably not the right career for you.
If you are reading this and you have any other regrets or suggestions please feel free to post them below in the comments box.