I did my first game under lights recently and there were a couple of differences.
* Watch (Spintso ref watch) was less easily visible sometimes with the shadows. Make sure to know how to use the backlight.
* As previously mentioned, looking up at ball would be glaring, but you don't need to be looking there anyway.
* Shadows can be a big of an issue, so I tried to move around more at ruck time just to be sure to see everything.
The biggest difference I found was that the game started so late in the day. I'm used to morning/early afternoon and so making sure your energy and concentration levels are up by the time the match comes around is key. I took it pretty easy for the day in preparation and had a pack of jellies with me before the game for an extra energy boost.