<3
Here's a 473. <3
The best way to photograph a beam - no matter the camera - is to use some sort of fog or smoke in the air. This is tremendously effective when the laser power is lower and you can even get great beam shots from 5mW lasers when they have some particulate in the air to pass through... and considering you can get a decent fog machine for around $30US, it's a small investment compared to most lasers in this hobby. Well worth it imho!
Another thing to consider when photographing more powerful lasers is some sort of beam stop to minimize backsplash of light off where the "dot" is hitting.
Different cameras seem to have different sensor response to colored laser light and so if you have multiple cameras, you can try different ones to see which is "easiest" for you to accomplish your goal. I use an iPhone camera because it's handy, but my wife as a point-and-shoot camera I'm going to try next time as an alternative.
Seriously though... consider a fog machine. It'll make it much easier for you.
Be safe and have fun!