Avoid re-starts and placeholders. Re-starts are when you begin to talk and then back up and start again, like this: "So then, well, as I was gonna say, uh let me put it this way." You're starting that sentence three times.

Placeholders are the sign of a poor structure. Placeholders sound like this: "This part, well, we'll talk about that later." or "After lunch we'll discuss that,". I would encourage you to not bring something up if you aren't going to talk about it until later. Leave it out until it's time to discuss it.