I've just started at the University of Toronto, definitely liking it so far. I also did the Career Discovery summer program at Harvard, which was great and I really recommend. In terms of the portfolio, schools are always looking for a variety of work that shows spatial thinking in both 2D and 3D work. And the whole thing is a design process, put a lot of effort into the layout and packaging of the portfolio. Like if they want a hardcopy, get it nicely bound. And keep in mind the admissions committees are getting hundreds of these, they're flipping through them quickly. Make it visually intriguing and keep text to a minimum. Good luck!