Most of the time I paper piece using very lightweight interfacing (with the pattern traced on) that I just leave in place. This works great for wall hangings or hotpads, etc. Not to good for baby quilts or things that will be handled a lot (it makes it too stiff, IMO).
One thing that I've just learned in the worst way possible is NOT to use a ballpoint pen to trace the pattern (what what I thinking??). Not only can you see it from the front, but it has a way of bleeding onto the fabric even after it's been 'removed' -- and no amount of soaking, hairspray, etc, etc, will get it all out.
I've just thrown out a lovely quilt because of this. Completely stupid on my part, for sure. :cry: