On a technical point (re Steve's post), at one time I had a pile of CDs and used to pick tracks off each - which was time-consuming, error-prone and panic-inducing. Then I burnt CDs with the tracks roughly in the order I intended to use them. Now I pre-embed the sound clips in the Powerpoint that displays the pictures of singers, song lyrics, broadsides, weird ballad illustrations, etc.

I also edit some (though not all) of the recordings. You don't really need to hear seven comparative versions of 'Cambric Shirt' from beginning to end.