I wash/dry the panel, then spray with a mixture of 4 parts water to 1 part vinegar. Gets the wrinkles out. If it's tiny panels, like the morrison kitty panels, they were just an 1/8" longer than wide so I use the Hole in the Barn Door quilt block pattern then it was not noticeable that the block was longer. If it's a long panel that you want to use in the center of the quilt like a medallion, then I add a wide border to it then trim it to a workable dimension like divisible by 2 or 3. Makes it easier to use block patterns after that. I just did one that that's what I did. It winds up framing the panel.