This works for many non-doujin pics, of the kind you would find on Danbooru. Not so well for game CG.
1.
http://iqdb.org/ 2. Upload pic.
3. If it's not found, you're fucked.
4. If it's found, click the thumbnail.
5. Notice colored tags, green=character names, purple=series, red=artist. Click on artist's "?" to find his site.
6. Even if there's no red tag (no artist), sometimes the source field shows where the pic came from, which may be the artist site.
7. Enjoy the SAUCE
& Thanks for the dump!