Honestly I just kind of got into VN's with Katawa Shoujo (can't wait for it to be finished). After that one though I've been trying to build my collection.
My first was actually Ever17...set my standards a little high I guess. Lord.
Read it first because I saw the famous Tsugumi "why is she in a washing machine" picture. And boy, I really did want to know why. To this day it's still my favorite.
I can't really remember which one it was, I think it was either Ever17 or Tsukihime.
Though it's highly possible that it was also just some generic visual novel with 90% porn, 5% plot and the remaining 5% lost somewhere.