Use 'that said' to contrast with what you've just mentioned, showing a different perspective or unexpected point. The car is really old and beat up. That said, it still runs surprisingly well.
Pro Tip 2/3
Softening Disagreement
Apply 'that said' to soften the blow when you disagree or point out a downside, making your criticism sound less harsh. Your design is creative; that said, it may not appeal to older customers.
Pro Tip 3/3
Change of Direction
'That said' is a signal that you're about to change direction in your argument or add a caveat to your previous statement. He's not the most experienced candidate. That said, he has a lot of potential.