I'm a new teacher. Of the 1,000,000 things I could be doing better, what should I do first?

In summary:

I'm new to teaching. At the time of writing, I have 2 weeks of student teaching under my belt.
I can't do everything at once, so I'm practicing one skill at a time.
My focus for the first two weeks was on learning names & starting conversations with students. It paid off more than I expected.
I don't know what to focus on next. Last Thursday I felt like I bombed a whole-class math summary discussion, and I don't want to sweat like that again if I don't have to, so maybe a skill in that department? By reflecting on how things went and working with my mentor teacher, I'm sure I can find the next skill to focus on. But...
I wish there was a clear guidebook for the first 10 things to work on as a new teacher. I've been taught a lot of theory, but it's all too complicated & intertwined to implement all at one time. I've been told how to get from good to great, but how do I get from drowning to competent?

Two weeks ago, I stood in front of my classroom for the first time. I took a deep breath, and...

Fight or flight.

For the past three years I've been studying the theory of what makes great math teaching. But standing in front of the room, all that theory was gone.

I think I did alright, all things considered. But teaching is extraordinarily difficult, and I know for a fact that I didn't accomplish everything (or, for that matter, nearly anything) an experienced teacher would have.

I can only fix one thing at a time.

I've known this about myself for years. When my golf swing was broken, I used to try to change my stance, grip, and takeaway all at once. It never worked. But when I focused on just my stance, soon that change became automatic and I could move on to my next goal.

So, at the beginning of the school year, I chose one goal for myself: Learn all of the student's names. And talk to them.

That on its own was plenty difficult.

Names have always been hard, and making small talk even harder. (I'm a computer person first, and always have been.) But by setting a single goal for myself, I've been able to focus on it and achieve quite a bit.

I made flashcards for myself to study after school, challenged myself to hand out name tags at the beginning of class, and appologized for my mistakes when I made them. I've done my best to start conversations with students before, during, and after school. In the hallways and in my classroom.

Am I perfect? Far from it. But the focus has helped; I've been doing better at these things than I imagined I could.

What's next?

My undergrad years were full of good teaching advice. But all of it was connected into one big web of ideas. It's a tangled mess of concepts to juggle in your head, all at the same time.

But as a new teacher, just starting out, trying not to bomb completely, it's impossible to execute everything all at once. Nothing is automatic, and I can only really practice one thing at a time.

Last Thursday I had an experience than is pointing me in the direction of my next goal. I gave students work time on an assignment and then went to discuss the assignment as a whole class, and realized I didn't have a clear objective. Which meant I had to spend 25 minutes sheparding a bunch of kids while I was still stumbling around in the dark myself. I was sweating bullets.

So, as student names & conversations become more automatic, I think I want to shift my focus toward improving the way I engage students in math content. But I'm not exactly sure how to achieve that; what, precisely, should my next goal be?

I want a guidebook.

All of the education theory I've learned during undergrad will no doubt help me go from good to great. But how do I get from drowning to competent?

I'm sure it's personal, and I can figure it out myself—especially with help from my mentor teacher. But it would be great if there were resources out there to help with the very first days of teaching.