Reinstalling cloth headliner

My headliner is all wrinkled and whoever put it in did a very poor job. I am trying to reinstall it to make it look better. It was not hooked over either the front or rear window and just tucked under the gaskets. I have removed the back window to start tucking it on the little teeth to hold it in place. Any advice on getting and keeping the wrinkles out? I will also be doing this by myself so any tips on doing it with one person would be helpful as well. Thanks!!