I think =

I reckon/ I would say
For sure, in my eyes it's really important because without it

Begin:

To kick off/ First of all

Adding:

Another thing is/ On top of that/ As far as i know/ To my knowledge
Emphasize:
In fact/ Here's the thing/ As a matter of fact
Giving example: You can see this with
Contrast:
At the same time/ That said/ Mind you