I partially used American Duchess's instructions and then ended up improvising. http://americanduchess.blogspot.com/2012/04/v101-how-to-make-miniature-portraits.html
What I did was resize some images I liked to 30x40mm, (previously purchased on etsy some 30x40 cabochon mountings), covered the print with Modge Podge, and then once it dried, using Modge Podge to glue the cut out paper to the mounting.
They turned out kind of cute!
I couldn't resist using the portrait of Mrs. Russell again (on the left in green) because I love it so much, even though I have a gorgeous pin of her made for me by my friend Gen! :-)
Also, I love the regency dude in the sunglasses. Too cool!
I need to pick out some more portraits to try next!