Hi ekmoore,
I don't have much experience as I haven't yet started my MLIS program, but I recently found out that I have been accepted to all three schools that I applied to (UBC, UW - Seattle, UW - Milwaukee), so I have some (limited) experience with the application side of things.
1) GRE. I only applied to schools that didn't require the GRE or where it was optional, so I didn't take it.
2) For the SOP, my main strategy was to put as much personality as possible into it. What makes you different from every other person out there who wants to go to Library School? What would you bring to the profession? Do you have any unique/niche professional goals? Be wild! Be inventive! But also, do your research, so that you actually know what you're talking about! I read a lot of blogs from current and former MLIS students, several professionals, I went to my local library and chatted with some current librarians on what their day-to-day work was like and how they viewed the profession, and I made sure to incorporate some of this information in my letter.
I know that's pretty vague advice, but that was essentially my strategy and it worked pretty well for me.