Are you using steam or are you just using lots of starch? The pressing should dry out the starch. You will have much more accurate cuts if you make sure you press the fabric until it is dry. If the fabric is still damp after you press allowing it to air dry may allow it to dry with wrinkles in it.
i second what Peckish said. Let the starch soak into the fabric fibers before ironing it. If you spray and then iron immediately, you will just iron off the starch.