Here are examples of the three types of leads. I was working on a piece about "firsts," and I chose the first time I slow-danced with a boy, who was my big crush at the time. These are the three different leads I wrote for it, actually in reverse order of how I wrote them.
Action
My heart pounded like a jackhammer against my ribs, as I started across the gym floor. My steps were timid, hesitant, yet I tried to move quickly, eyes wide and alert as I looked around for him. All around me were bodies, pressed together in little clusters. I squeezed past them as I made my way to the middle of the gym...
Dialogue
"Oh come on, Julie, let us ask him."
I shook my head. I could feel myself already starting to blush.
"Come on!" my friends begged. "What have you got to lose?"
I hesitated. "What if he says no?"
"Well, then he's not worth dancing with, anyway. Besides, he'll probably say yes," insisted Jenn, as if she had any more wisdom about the inner workings of a 12-year-old boy's mind than I did.
I shrugged helplessly. Realizing I had no other defenses, they continued to push. "Let us ask him," pressed Erin. "C'mon, you know you want us to."
I sighed in defeat, but even as my face started to burn, a little smile tugged at the corners of my lips. "All right."
Setting
The gym was stuffy with the bodies of a hundred some seventh and eighth graders, but the heat wasn't what was making me sweat. The Christmas dance - only the second school dance I'd been old enough to attend - was winding down, and I still had not danced.
What I find funny is that I started with the last one, with the setting, then wrote the dialogue one, and then wrote the action one... but actually, if I were going to write a rough draft on this prompt (which I was going to, but I changed my mind and am gonna do a different one instead), I would probably just end up combining them, since they kind of go in order of what happened anyway. Apparently that is why I'm so wordy, if I'm taking three short beginnings and combining them into one big one on every scene LOL.
Anyway, those are some examples of what the three types may look like for the same scene.