There are several tutorials and discussions on Material Safety in the Matrix - it’s a good place to start your research.
Read THIS first.
Check this list:
http://atxhackerspace.org/wiki/Laser_Cutter_Materials
Only then should you watch this video:
For safe and tested materials, do a search in the Beyond the Manual category for whatever material you are thinking about using, plus the word “settings”. It will pull up other people’s results and some good starter settings.