You'll need to do text and image research at the same time, because background research helps you know what images to look for. Try making a mind map to plot your topic, the subtopics, how you'll research each subtopic and some of the problems that your designs could solve. Practice with the one below, and check out an example here.
Each subtopic will be connected to text and image sources that help you understand the bigger picture and give you visual inspiration. Check out this book chapter for more info about mind maps for designers.
Porter Campus
1801 Massachusetts Avenue
Cambridge, MA 02140
617-349-8070
South Campus
89 Brattle Street
Cambridge, MA 02138
617-349-8850