natural light

See the dark areas/shadows around her neck?  That can be fixed by using fill flash -1.7 stops or so. The flash fills the shadows and is not noticeable.  Fill flash is very useful.

Flash is a tool.  Rather  than patting yourself of the back for not using flash perhaps a better approach is to determine how and when flash is appropriate.

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RonFrank
http://ronfrankweb.weebly.com/index.html