I've been up to my elbows in beanbags lately, and I've gotten a few questions about freezer stenciling on them. I usually point people to this tutorial, and I've even talked about it here before.
At any rate, here's a full tutorial of my own on how I freezer stencil.
I buy my freezer paper at WalMart. Target and our grocery stores never seem to have any.
I also like Tulip matte fabric paint. When it dries, it's not too stiff and only costs about a buck at Michael's.
I start by tracing my stencils onto the dull (not waxy) side of the freezer paper. You can also trim it down into 8.5" x 11" sheets and feed it through your printer.
I carefully trim each shape with an X-acto knife. Be sure to set aside and save any inner pieces.
Then I iron, waxy side down, my freezer paper stencil to my fabric. A few seconds is all it takes for it to adhere.
After my stencils are cool, I apply 2-3 THIN coats of fabric paint, allowing them to dry in between. If the paper gets too wet with paint, it will start to release from the fabric and the paint will bleed outside of the stencil.
Be sure to either iron another piece of freezer paper to the back of your fabric or paint on top of newspaper or cardboard so your paint doesn't bleed through and you end up with an 8 on your granite countertops.
ps. A Mr. Clean magic eraser takes it right off!
When your final coat of paint has completely dried, carefully pull the paper away from your fabric.
Iron over your paint to set it, and you're done!