If it's a step up in level, be prepared to walk or portage around the rapids. Plan your trip by confirming paddle buddies, checking release levels and weather conditions. Scout any questionable rapids. Always kayak with another paddler who is able to rescue you if you get into trouble. Dress for the weather and water temperature.
Layers work well.
Hypothermia is not uncommon. Don't drink and paddle. Drinking on the river is never done. Yet, a beer and some munchies at the take out are not uncommon. Paddlers often face more dangers on land than on the water.