One thing that pops into my mind, is if you are bank fishing at a boat launch, PLEASE don't block the ramps, we have had it happen numerous times that bank fishers are sitting between the ramps with their lines in front of them, this results in the boaters not having any place to land their boats.
For boaters, have everything ready before you back the trailer down the ramp, this makes for a speedy launch and makes everyone happier.
Take your trash with you. This includes old line, hooks, everything.
Watch your casts when in a crowded area.
Offer to help someone if they need it.

Another subject that needs consideration, might be boater ethics, this is a subject that also needs to be approached. I have several pages of etiquette on my web site that might help a little, have a great day.
Banock