start by taking the basting out. Make sure the back is starched and ironed flat. Be sure to tape the back down to the floor with masking tape or painters tape (right side down).
Put your batting down next (I usually tack the corners down with tape to keep it from moving.) Put the top down (right side up). I usually pin rather than baste. I use my long ruler to work out any kinks in the top to keep it smooth. I have become a fan of spray glue to sandwich my quilts with a few pins to keep it held together solidly. Given all that you have alredy done flip the quilt over, take out only the biggest wrinkles by taking out the basting from these areas and see if you can work them out using a yard stick or you long ruler to move the wrinkles out. Start at the center and work to the outside. Good Luck and let us know how it goes.