I'm in LaSalle doing foundations, handling freelance jobs and
had a good job in a small Graphics/Advertising Firm. (Quit due to
school)
Don't worry too much about what to put your portfolio. Whatever
you've got, put them in. Most importantly, have a variety, a range,
a series, or all even. It's the presentation that really stands
out. (If there is) And the amount of 'bullsh!t' you're willing to
come up with. In this industry, it's that way, like it or
not.
As someone mentioned. If you're going to have a really nice, neat
portfolio. If the first work is presented in portrait, keep it
consistent. Or, better still, be yourself, bring your sketchbooks
and present.
When I submitted my portfolio, for foundations. I had some of my
works, my old sketches, paintings, models, digital images and even
illustrations in it. They said 10. I gave em 35.
You say you're keen. I hope so. Cause it's not so easy doing
graphics/advertising. Either way, even if you take up Graphics as a
major, you'll still be posted/hired by some Ad firm.
One more thing, apart from all the mumbo jumbo in the folio.
Remember to at least show a few different works using different
programs. To show your experience and skills with them. Since you
plan to take Graphics. Photoshop, Illustrator and InDesign is a
must. Other illustration programs would be a bonus. Though I'm not
sure about Freehand. Most companies still use them.
And, if you do get into LaSalle, please don't become one of them.
(Poseurs) 
