Everything they said - but also - get into the habit of holding down your uncut material and lifting out your cut pieces - because if they didn’t cut through you can literally close the lid and just hit the cut line again and it will be in exactly the same place (unless you knock the laser head). The camera image may look off, but the laser will cut in the same place.
It’s a good habit to get into because even in a perfect world material is sometimes tricky (extra fibrous, expanded from humidity, a touch more dust on your lens than you expected, etc.) and a cut can fail in spots.
Using these will make that much easier because your material definitely won’t move!