So you are ready to create an audition portfolio for an art magnet school or post secondary art school. Congrats! Depending on the school you will need at least 10 pieces of show quality work. But the portfolio is just part of the process. Make sure your attendance and your grades are great. Most schools look at more than your sketchbook and your portfolio to determine your acceptance to their school.
Learn all that you can about the school you wish to attend.
Go to their websites, orientations, workshops, talk to students & teachers, & visit. Think about what kind of art you like and create - and write an artist statement. You can find out more about artist statements HERE
You cannot begin working on your sketchbook and portfolio soon enough. Take 100 photos every day! Draw every day! Keep your sketchbook with you at all times! They will help you find YOUR voice.