Most of the time, a safety briefing is pretty simple. You find the topic, you research it a bit on the net or at your unit, bring some statistics, facts, recommendations, etc...
You have to be well spoken (all ranks might attends...) ,but don't be stressed out, there is no point. Look at people that seams interested in what you say.
For your topic, think about the tools that you use and the hazards that one LCIS might encounter (don't fool with capacitors ,transfos, solder smoke bad for you, don't burn yourself, safety glasses, I don't know.
What I can say is that at our shop (construction unit), we get to do a briefing once in a while, and no big deal. Just look like you cared about your tasking, you searched it and somebody will learn something, that's for sure...
Good luck!