I applied in Canada. To a Design program (really, it's just called Design) and the Portfolio Day it's really important. I don't know if it's the same, but do you like take what you have done so far and they critique your portfolio and tell you what you should keep or do better? that's what it was like for me anyways. For the one I applied to, the most important thing was variety, and yes, it's important to put your best stuff, but also the variety so that they can know you have a good technique. I had stuff from painting, drawing, digital stuff (photoshop illustrator) sculpture, photography, some t-shirts I designed, logo designs. (but I guess that also depends of the program and school you are applying too.)
Also, for me, I don't have an excellent technique, i mean I really suck at life drawing and I still managed to put some "expressive life drawing" that looked really cool! After all you are going to school to learn and become better at what you do, so yout technique doesn't have to be perfect.
Sorry it's so long, I get carried away!