This may sound like a link bait title, but there is a lot of useful stuff buried in the archives of my blog that is there free for you to use. Click the "3 dots" at the top right of the site to access a drop down menu with more options. Among them: 

And of course there is the full version of my book about presentation design that can be accessed free of charge.

Art: Jan Davidsz. de Heem, Still-Life of Books, 1628