For us to advise, you'd need to tell us your Website's requirements; otherwise none of this matters if it works for you.
I dunno how much search engines parse filenames versus reading metadata.
But since you asked:
* I prefer mixed case, without spaces, e.g. RoyKaye. That way, nobody has to try and figure out whether they're from R.O. Yakaye, or R. OyKaye, or Royka Ye .. - I realize lower case is in fashion, no-doubt due to the many iPhone-like devices that make it an extra bother to use mixed case, but that doesn't make it good.
Spaces are good for readability, but wreak havoc when you are using command-line tools, or in URLs..
The other word of advice: make all filenames unique, so you could export your whole catalog into a single folder and never have a naming conflict. Not that you would, but if you send an email to someone they can give you the filename back which will allow you to unambiguously locate..
FWIW - my naming convention:
is the filename for shot:
* taken 2014-10-31
* by me (RC)
* at 7:01:02 am
* with my 2nd Nikon (NB)
* original image number 1234 (original filename _DSC1234.NEF).
* NEF (file format)
* If all photos exported to same folder, without renaming, there would be no naming conflict, and alphabetic order would be just the order I want (even if shoot includes photos from another photographer, or a second camera..).
* filename is informative, but not dependent on anything that could ever change.
* I can trace filename back to original on card, in case I need to do card recovery.
* Filename components are uniform in length, which means things line up when viewed in a list.
* No spaces, and alpha-numeric only, means filename is always the same even in a URL, and never needs escaping or quote-wrapping..
* Long (I considered variations with delimiters, but opted for short(er) n' smushed..).
* Difficult to read, and I may be the only one who knows what all the components represent (e.g. 'NB').
PS - I usually don't rename upon export, other than maybe adding a suffix, e.g. "shrunken-for-email", but you can also have 2 or more different filenaming conventions:
1. Source filenames (which may have no objective other than uniqueness, and yeah: I know - some people don't even care if they're unique, but I do).
2. Exported filenames (which can include all info required to uniquely identify the photo - in case of feedback in the future.., plus more user friendly stuff, like genre, photographer's name, shoot-affiliation, etc.
PPS - I use the convention: upper case extension for out-of-camera originals (which would include DNG if I converted out-of-camera-originals), and lower case for derivatives.
Many thanks for your help - I have something to go on