When using cut-off wheels, angle it so you are not looking inline with the cutting disk. When it shatters there is no telling where the broken parts will fly.

And I'll third the use of eye protection. For low-rpm or quick cuts with the dremel I don't wear hearing protection (for longer duration I will wear hearing protection), but always eye protection. I keep safety glasses on my drill press, scroll saw, belt sander, with my dremel tool, lathe and mill, and a couple of extra pairs beyond that incase somebody else is in my secret experimental laboratory, uh, I mean modeling room. A lot of them sitting around but I never have to look for them.

Hogflyer