According to the author / text, …
To begin with, … / First of all, …
For example/instance, … / As a matter of fact, …
Nobody will deny that … / That is why … /
Firstly, … / Secondly, … / Thirdly, …
Therefore, … Furthermore, … /
Additionally, … / Moreover, … / Also, … /
Another argument for / against is …
On the one hand … / On the other hand …
However, … / Nevertheless, …