Searching Google for images is quick and easy. The problem is that that the descriptions for them are often unreliable or incomplete. But libraries and museums often digitize materials and provide accurate information. There are many options out there, but a few that might be useful for historical costume research are:
The library subscribes to a lot of resources that have what would be considered primary source visual information - newspapers like the NY Times going back to 1851 and ArtStor. This is a selective list of them.
This video demonstrates how to use free primary source search tool Digital Public Library of America (DPLA).
This video demonstrates how to search for digitized primary using Google and where to find UWM Libraries digital collections and primary source databases.