Safety on the James River American Whitewater Assoc. Code.
Below are my thoughts quickly written as they occurred to me. For complete whitewater safety including group dynamics see the above link.

Strainers are those things like tree branches that let water though, but have a tendency to hold you underwater. They don't have to be above the water and are very hard to see in the wave patterns. Float and swim on your back and keep your feet up.

No walking in any thing but slow moving water. Foot ware is a must there is a lot of broken glass.

Keeping you feet up and pointed downstream when in rapids helps avoid getting tangled up in things you can not see.

Fishermen have died in the city due to hitting their head while slipping on the rocks. If you think you will slip stay low to the ground. Tennis shoes work well. Slippery stuff can be black or green wet slime or moss etc. Dry moss is not so slippery but once splashed upon watch out. A hint for those hiking in streams. Those hard soles found on hiking boots have an all or nothing grip. Tennis shoes and their like kind tend to start slipping slowly and may give you time to recover.

Keep the person behind you in sight. That is the person that will help you if you have any problems, not the person up ahead. You can slow down usually by paddling to the slower current on the sides and behind boulders.

In the past several people have had to quite because they did not drink enough water on very hot trips.

Don't tie loose hanging ropes to your tube or between two tubes. Getting snagged is very easy. Don't tie anything loose to you.

Swim in deep water like CooCoo rapids and in swallow rapids float on your tube.

Get off the river in a lighting storm. I had a friend die in a Roanoke park on a sunny day when they heard thunder in the distance, but did not see any lighting.

Rivers bed rocks provide direct contact with ground currents. You may want to sit in your plastic canoe while under a bridge. Staying among a group of trees may be your only choose. but not under the largest one please. The rule of thumb is the danger zone of a tree is equal to it's height. If things get bad, you can squat with your feet together between two of the smaller ones, hopefully on woody or grassy ground. Note before hand where the City of Richmond shelters are. Get near the parking lot by 3 or 4 PM so you make a run when the clouds come.

The Old Dominion Appalachian Trail Club Find the list at the bottom of the page of everything you would need including first aid kit. I'll update this address as it is changing soon.