Sunrise Wedding on the Beach

I have a wedding tomorrow that starts at dawn on the beach so we can get shots with the sun coming up behind the portraits. I'm planning on adjusting for ambient light and using the flash for fill. Does anyone have any suggestions or words of wisdom on how to pull this off correctly? Thanks

Correctly is a subjective term in this case. It depends on how you want it to look.

I would think that it might be a good idea to underexpose the background a bit, to bring out the colors, then light them up with flash.

Should have practiced beforehand, but I think just scouting out the beach and seeing where the sun actually comes up. The reds only come out at the nearest to the horizon. Be prepared to go extra early. Fill flash is a good idea. Take close ups and long shots.