To improve your chances of finding high quality, copyright-friendly images:
Starting from the "Advanced Images Search" screen -
Under Size - Return images that are: Larger that 1024x768 to limit your results to images of larger sizes (giving you the ability to zoom in closer without fear of pixelation).
Under Usage Rights - Return images that are: Labeled for reuse with modification - meaning that the copyright owner is okay with your using the image and changing it as well.
Don't forget - You'll still need to cite this image!
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