You can begin the introduction by using a hook, or a thesis statement about what you will contrast and compare. Next, you may state what you generally found to be similar between the subjects of what's being compared, while you then state what you generally found to be different between the subjects of what's being contrasted. Afterwards, you can always add ideas and bigger themes that you'd like to include about what you found, and make sure to elaborate on your general comparisons and contrasts. Remember to follow with a smooth transition to your first body paragraph.
