What should I look for when evaluating a free comic font's license?

Pay close attention to the license terms. Common licenses include ‘All Rights Reserved,’ ‘Creative Commons,’ and ‘SIL Open Font License.’ ‘All Rights Reserved’ means you can’t use the font commercially. ‘Creative Commons’ licenses vary; some allow commercial use with attribution, while others don’t. ‘SIL Open Font License’ is a permissive license that generally allows commercial use.