Forget about cache. Art schools don't care whether you use spray paint, oils or crayons. They care about results, and how effectively you can adapt to the tools at your disposal to create interesting art.
Obtain an appropriate folder or notebook. The type and size of your work will determine the type and size of the portfolio, or folder, you will need. For example, small prints can be affixed to the pages of a notebook, but large paintings or drawings will need a large folder. Obtain or make one large enough that you will not crease your work.
Assemble a good variety of your work. Interviewers are looking for a few basic things: your skill at transcribing what you see, so avoid fantasy work; your ability to use, blend and mix colors in the types of paints you use, because the more paint types you can you effectively, the better; your ability to create "round" looks and shading on a two-dimensional surface; and any other major art forms, such as sculpting or carving, that you can do. Digital work and photography, unless you print it yourself using a variety of techniques, will never be enough to get you into an art school. Use them only to round out or supplement your portfolio.
Cut the chaff. Don't use three versions of the same painting, unless there are major stylistic differences, such as one in gray scale, one with realistic skin tones and lighting coming from a distinct location, and one in bright pop style. Use only the best example, or two at the most, of each type of work, such as color, shading, anatomy and still life.
Rely on more than your portfolio alone. Plenty of very rich, very famous artists have little talent. The art of selling your talents through the gift of gab is alive and well on the art scene. Learn the lingo by reading both counter-culture art magazines and high-society coffee table art books, and use it. Sell yourself as an artist by calling yourself an artist.