Make sure to get a zinc installed on the hull. Many freshwater hulls lack one. I do not consider myself knowledgeable on correct methods of zinc anode installation, but I can recommend a place to find said info, if no one else on here steps in. Wash the hull down after every use. If you get it while still wet, a good hose down will work. Other times, salt away, or a similar product is useful. Flush the motor after every use. Be pickier on hardware selection. NO copper or brass or any other copper alloy anywhere on the boat. Your electrical system will also be one of the first to show damage, so a good going over of that might be in order.
I personally prefer welded hulls in saltwater (when I ever get around to fixing the 14' Alumacraft I picked up for a song, the pictures will show why), but with proper maintenance, the riveted hull will be fine for a while.