Sejuani is now my favorite of all champs. All of season 2 I was stuck in that "Elo Hell" and felt I was stuck in Elo Hell for Season 3 too.
Late last season I started playing with Sejuani and I won a few games, but never put much into her. At the start of Season 3, I picked up Sejuani and have won 9 out of 11 of my games as her. Sometimes you just cannot help do anything but accept a loss when every other lane loses and they snowball out of control. Regardless, with a positive mind set and just accepting the fact that players mess up from time to time, I learned that with enough time in a game, I can build so much health and build to the occasion as Sejuani that I can dive turrets at any time, usually last long enough in team fights for prime objectives to die if focused properly, and if my teammates work with me in order to secure a kill. Only problem I ever have with Sejuani is early game before level 6 if counterjungled or if teammates refuse to work together.
People underestimate Sejuani so much, but once she gets that ultimate everything just falls into place, especially if you have teammates like a Katarina or Shyvana that can sync with Sejuani's ultimate to do a lot of guaranteed damage.
Overall, Sejuani has become my go to gal for any jungling needs. I also have been trying out Zyra in normal and just now in ranked and I have to say that I absolutely love her as support. I used to love Nidalee support, but that seemed to die out and the Zyra approach being so aggressive has drawn my attention more than anything. Still never tried Lulu or Leona as supports so might want to give them a shot one day, but at this moment I think Zyra will do everything and more in a support role at low Elo.