How does one clean the headliner without damaging it? I have couple stains and I have no idea how to remove them. Thanks guys.

 

Assuming you've got the cloth headliner, I would treat it the same as you would any automotive textile. Start with soap and some water and slowly move up to more aggressive solutions.

Put a towel down so it doesn't drip.

 

don't spray any cleaner directly onto the headliner, it can potentially eat through the adhesive. I would spray it onto a towel and blot the stain. Meguiars APC diluted should take care of it, just make sure you don't use a ton of cleaning solution.

 

Mine has water stains from the sunroof being cracked open? Any suggestions?

 

303 Products Carpet/Upholstery Cleaner and Spot Remover with a mf towel. Like the above person said spray/damp the mf towel and lightly wipe the area and blot dry.