Yes I did do many stuff to improve myself this year and here's some of them:
1. I read Doing Right by Phillip Hebert
2. I don't know which year you are in and if it will be possible for you but I was graduated last year so I started working as a pharmacy assistant almost 30hrs/week
3. I went to career counsellor to ask advice on how to improve my essay
4. and this year I practiced interview almost everyday for at least 3 weeks? (how much you need to prepare also depends on how comfortable you are with the interview, I guess, I was really not comfortable with interviews because I get shy and nervous, so I needed to prepare a lot)
That's all I can think so far, hope it helps! Good luck next year!
BTW: I got in both UofT and Waterloo as well. I'm from Ontario. UBC is definitely my favourite school because Carol is the most helpful and nice admission officer among all these schools from my personal experience. I do love UBC campus like it's so much better than waterloo's and uoft's. I love Vancouver so much. And I paid 2000 too lol. However, my parents want me to stay close and my friends are all staying in ontario. I might give up my UBC spot this year. So ppl on waiting list, don't lose hope yet! but be patient plz lol, cuz i just got my uoft's today so I really need some time to make up my mind.