Actually: to give surprising or new information /correct some information.

Anyway: I am going toe change topic/return to the original topic or finish the conversation

Basically: I am going to summarise the most

Mind you: I have thought of something that contradicts what I have just said.

If you ask me

By the way: I am going to introduce a new topic-change the direction of the conversation

To tell you the truth: about to give my opinion- and it may be insulting

Come to think of it: I am going to add something I have just remembered/though ot