jul1e, welcome to the BOS forums. we hope ur time spent in the forums are helpful, informative, enlightening and enjoyable!
i used to do art in yr 12 (but dropped it, cos i had too many units), and i experimented with sculpture, drawing, digital imaging and photography. my concept was 'balance'.
first, i suggest brainstorming some ideas about what u want to do. perhaps a global issue, a personal view, the exposing of observations, etc...really this is up 2 u.
anyway, i assume that u have some experiences in print-making...
so i would suggest that find a major theme that print making expresses well. perhaps a theme that requires great and fine details, or quite the opposite.
ive brainstormed some:
-the fun and fury of nature
-the human body
-patterns - a life story...
-balance
-social unrest, injustice, inequality, etc...
but, above all, use media that u feel comfortable with, AND/OR media that you feel will express ur major work most effectively.