Agreeing

 It's a good idea to vary your expressions when agreeing. Here you can find a few ones to use in dialogues:
I entirely agree
I absolutely agree (on that)
Definitely!
You’re right.
You’re absolutely right.
I think you're right!
I think that's a really good point Sure
That’s a good point
That makes sense
Yes, that sounds sensible
I really liked what you said about…
I'd definitely agree on that (notice "would") I suppose your right!
I wouldn't argue with you on that! :) That's precisely my point
That's exactly my point! I don't quite agree with you on that
I don't quite agree on what you said about
I don't quite agree on the part about...