Here's what I prepare when I teach a yoga class:
A quick joke or story from my day: I saw my new favorite bumber sticker today--"Unless you're a tattoo, get off my ass!" Settle down into your seated posture, and give yourself all the room you need.
Some combination of seated meditation/body adjustment/breathwork: To give yourself more room, bring your attention to your spine and separate it into segments. Lengthen first at your low back, next in the lower middle back, next at the vertebrae between your shoulder blades, finally at your neck.
A quote to set the tone or else context for the intention: You may choose an intention to gather something unto yourself today during your practice--peace or strength or courage or community, something like that. Or you may choose an intention to set somethin free--worry or fear or upset or hurt or loneliness, something like that. Of course, you could always dedicate your practice to someone or something else.
A warm-up sequence or theme: A sequence of spinal flexion/extension. Start with movement from childs to hands/knees, then move through Cat/Cow, then recreate that movement in downdog, and again recreate that movement in updog.
General poses I want to flow through: No warrior I today, spend a lot of time working spine in crescent lunge, Do a flipped dog today instead of fallen warrior. Mostly, I watch the class and move into poses that look called for.
At least one 3-5 minute hold: Pigeon or frog or cowface.
The reflective song I'll play in the held pose: Love is Looking for You by Miranda Lambert
The upward prana moving song I'll play in a 3-5 minute shoulderstand: Someone to lean on
A Savasana metaphor: Anahatta Chakra
Closing quote: A perfect falcon, for no reason, lands on your shoulder and becomes yours.
Of course the trick for me, and what seems to differentiate a good class from an exceptional one, is how well I transition between the sections. Some days all the variables seem to meld together into an overarching theme. Class becomes alive, an act of creation. Others...Well, I can see the wheels turning in my head as look for the connections which somedays just don't come.
I remember a conversation with a wonderful massage therapist named Leslie Roach. She shared how in massage therapy school they spoke directly to "taking care of your instrument". Get sleep, eat well, clear your mind, etc. Those seem to have a large impact on whether the connections happen in my mind on those wonderful class days.