It used to be that if I connected my iPhone and clicked Import All in Image Capture, it would import only the new photos. Now it imports all the photos even though it recognizes that most of them are already imported and it shows a green checkmark on them. How do I import only new photos without having to select them one-by-one?
I don't think it's entirely possible although there is an Image Capture plugin for Automator that will let you do a number of automatic procedures. I can't say if this is possible but my guess is it will be difficult. Check out the end of this article to see if this is a path you want to take. The Many Miracles of Image Capture
That kind of smart import was built into Photos (iPhoto) as a part of the OS free suite of apps. I generally use that one for easy importing and sorting but some don't because of it's odd organization and storage of the photos.