I have been using the cardboard method (noted in the earlier post here, I can't get the link to work) on all the repairs we do. With this method, you don't need the baby powder and twists are less likely.
You can add the tag line attached to the cardboard for big kites. Two people will really help the process. The key to the cardboard is the keep the edge along the front seam to insure you don't get a twist.
I agree, slow down, take your time.