So, let's start with ...
I'd suggest we start with...
Why don't we start with...
So, the first item on the agenda is
Pete, would you like to kick off?
Shall we start with ...
(name of participant), would you like to introduce this item?

Closing an Item

I think that takes care of the first item.
Shall we leave that item?
Why don't we move on to...
If nobody has anything else to add, lets ...

Next Item

Let's move onto the next item
Now that we've discussed X, let's now ...
The next item on today's agenda is...
Now we come to the question of.

Giving Control to the Next Participant

I'd like to hand over to (name of participant), who is going to lead the next point.
Next, (name of participant) is going to take us through ...
Now, I'd like to introduce (name of participant) who is going to ...