Новая тема:

Today, we are going to talk about…
In this lecture, I’ll focus on…
Let me start by discussing…

Переход к новому пункту:

Now, let’s move on to…
The next point I’d like to discuss is…
Turning to…

Уточнения или примеры:

For instance…
An example of this would be…
To clarify this point…

Подчёркивание важной информации:

It’s important to note that…
What I really want to stress here is…
You should keep in mind that…

Подведения итога:

To sum up…
In conclusion…
So, what we’ve covered today is