Tag Questions with Linking Verbs
Solution 1:
You look a bit sacred, don't you? Or, You look a bit scared, aren't you?
She seems happy, doesn't she? Or, She seems happy, isn't she?
The usual rule is that if the anchor predicator is an auxiliary, select the same lexeme, otherwise select "do".
In your examples the predicators are not auxiliaries, but lexical "look" and "seem", so "do" is correct.