Pictures would be useful here. I agree with 1968 S, if you have excessive wrinkles in the headliner, something is not right. You should have everything pulled pretty tightly and very few wrinkles. Start from the rear and work forward. Use small but strong clamps to hold the sides. Get it fairly tight, then work the sides. When it looks good, get the glue out and finish it off. If you use Dynamat or anything like that, some additional spray adhesive will keep it from eventually falling down. Your mock up work should look like finished product. Get the wrinkles out before you glue anything.
