If you're at school and wanting to get into higher education to do graphic design or you're already there and looking for a job, this is the tip I give to everybody.
Employers and college interviewers are aways more interested in self-assigned work. Projects you have set for yourself in your own time are far more interesting as they say more about you than a curriculum project that was set for you by a school or college. I guarantee a self-set project will be the one an interviewer will pick out and talk about because, as well as being an insight into your personality and way of working, the truth is they will probably have seen the other standard projects so many times that day from other candidates that they'll be looking for something to keep them awake!
Design some film posters, start your own website, design some game characters or create a vinyl boxed set for a band you love...whatever it is, it will start a conversation. It doesn't even have to be what you might think of as graphic design: photography, portraits, 3D work...anything that shows that your creativity is part of your life, that you have a love for the subject and you're willing to spend your own time working on it because it doesn't even feel like work
Spend the time you are at school or college collecting anything you might have done yourself (flyers for parties, charity posters, CVs for friends) and you'll find your portfolio is much wider than you thought.