My teaching/speaking approaches with most subjects in front of classes/groups, regardless of subject:
I generally work out an outline of the talking points I want to cover so I don’t go in circles, over-explain (I have to watch that, especially on topics I know well) or segue to things I’ll actually cover later. And remind myself to stick to my well thought out preparations to keep the flow and balance right (so I don’t divert too far into yummy minutiae)
And comfortable enough with topic that I know broader info than what I’m talking about even if not including (meaning comfortable enough to speak to questions that come up or if things go more in depth on something)
Classes, I prep what I intend to cover. I’m WAY more relaxed if I feel well prepared. Mentally step through details. Then also ALWAYS have Plan A (the planned coverage) and Plan B (we go faster/slower) to adjust if pacing needs it or the mix of students calls for it.
The way I handle nerves, no matter the crowd or setting, is I get in the mindset I’m just sharing information with a group of good friends I know well (even if total strangers). I’m more relaxed and things flow better.
Sometimes things go according to plan. Sometimes they don’t. Either way, I sort of analyze things afterwards to see what I’d do the same or different next time.