1. BEGINNING THE MAIN BODY

Now let's move to the first part of my talk, which is about....

So, first...To begin with...

2. LISTING SIGNALS

There are three things to consider...First...Second...Third....

There are two kinds of...The first is...The second is...

We can see four advantages and two disadvantages. First, advantages.
One is...Another is...A third advantage...Finally...

On the other hand, the two disadvantages. First...Second...

3. LINKING: ENDING PARTS WITHIN THE MAIN BODY
That completes/ concludes...
That's all on...

4. LINKING: BEGINNING A NEW PART
Let's move to the next part which is...
So now we come to...
Now i want to describe...

5. SEQUENCING SIGNALS

There are (seven) different stages to the process.

First/ then/ next/ after that....

There are two steps involved.
The first step is...The second step is...

There are four stages to the project. At the beginning, later, then, finally...

I'll describe the development of the idea.

First the background, then the present situation, and then the prospects for the
future.