To show a process / steps in a process / parts
Firstly, secondly, thirdly...
Introduction / topic
I am going to talk about / the topic today is
Concluding ideas
To sum up / to conclude / to summarise
Moving to a different main idea
Now let's look at / moving on to
Overview of the lecture
First of all, ... and then I will go on to the ... / Firstly, ... lastly, ...
Concluding the idea
In short, ...
Cause / effect
So / Consequently / That is because
Expressing (the speaker's) opinion
I think / I believe / From my point of view
Stating opinions (not the speaker's)
It is believed / It is considered to be
Contrast
On the other hand / However / Although
