> To put a double-faced card into your deck, you have two options: You can put your entire deck in opaque card sleeves, as many players already do, or you can use the checklist card provided in many Innistrad packs.
> If you're using sleeves, it's pretty straightforward. You'll want to put the double-faced card in the sleeve with its front face showing, and take it out of the sleeve when it transforms. (Putting it back in is optional, at least until it leaves the battlefield.)