Standing out in the fit part of interviews

Hey WSO.

I've been practicing a ton on fit questions in general by practicing in the mirror (Yeah lame I know), and in front of the webcam non-stop. I've practically run through tons of different questions, and feel very confident now for my future interviews. I really just intertwine certain answers to what the firm is looking for as well as my previous internships (competence) but showing I'm open-minded and that I've attacked my previous weaknesses in general. 

All that being said, any tips for really standing out even more for the fit part? I'm worried I might come off as a buzzkill if I try to overplay the competence aspect. I really think the fit part of interviews matters the most because at the end of the day I want to be someone that the others want to have around which is the main thing I keep in mind. I've got a good smile so I try to use it when I can, lol. 

Cheers