Hereof, what kind of paper do you use with a heat press?
As a rule of thumb, most transfer papers will work with 100% cotton, 100% polyester and poly/cotton blends. The notable exception is 3G Jet Opaque, which will work only on 100% cotton.
Similarly, what side do I print on transfer paper? MAKING THE TRANSFER PAPER PRINT
You want to print on the dull (uncolored) side, not the shiny side which is tinted with color. Make sure the paper is not curled or bent at the leading edge. Remember that the image that ends up on your fabric will be a mirror image of what is on your computer screen.