The two main things to keep in mind when applying to the US are:
1) Rolling admissions means the earlier you have everything turned in (including letters of recommendation which can easily be the rate-limiting factor), the better. This goes double if you have average stats and are not a URM. Ideally you want your AMCAS to be in by June and all secondaries by about September. Try not to depend on an August MCAT score if possible, because obviously that'll delay things.
(Note: this advice falls under the "do as I say not as I did" category)
2) Do your research!!! You want to find schools that not only will accept Canadians (assuming you're not a dual citizen), but accept a good proportion of out-of-state applicants. Most of those will unfortunately be private meaning extra $$$ in tuition.
Speaking of the tuition costs, if you're neither a US citizen nor permanent resident I don't think you'd qualify for the same financial aid (ie. Stafford loans). If you're not independently wealthy, that's most *definitely* something to keep in mind and again do your research on. Applying to the States is quite expensive in and of itself, so you want to be sure you'll be capable of accepting any offers. Finally, understand that coming to the US will make it pretty unlikely that you'll return to Canada for residency.
Best of luck, wherever you apply! Since you're still U2 do your best to rock your classes and the MCAT, that way you'll have the most options open. And of course don't neglect to obtain health care exposure if you've been limited thus far.
Anyways, the list is linked in an above post by thewonderer.
