You must know how to swim.
Treat your canoe carefully. Don't drop it, drag it, or run into things.
A canoe is stable only when floating along its full length. Remember this when getting in or out.
Steady the canoe for your partner to get in.
Hold on to both gunwales when getting to your paddling position.
Paddle in unison; the bowman usually sets the tempo.
Paddle on opposite sides.
The stern man is in charge.
Put all gear into waterproof rubber packs and tie them in.
Dress for warmth and comfort.
Don't hold onto bushes! Use your paddle to hold against current or to pull you out of trouble.
In rapids or tortuous streams, the bowman is responsible for steering his end, and must initiate the immediate course.
Sometimes you must break rhythm or shift sides suddenly, therefore:
Kneel for greater stability in fast water. Rig your canoe with thigh & foot braces for still better balance and increased emergency power.
In white water let an experienced canoeist lead the way.
Have a spare paddle for each paddler fastened so that you can get to it quickly in an emergency.
Wear a life jacket...preferably a non-inflatable vest type...in dangerous water and in cold weather.
Look over questionable places from shore before attempting.
Keep canoe parallel to current as much as possible.
Where cross-current turns are necessary to avoid obstacles, always lean down stream.
Dump shipped water promptly to ensure stability.
"Discretion" is the better part of valor...line down or carry if in doubt.
Keep close enough to the canoe ahead to see what happens, but far enough behind to avoid his mistakes and to miss him if he spills or sticks.
Keep the group together. Be ready to help others.
Make the water work for you...not against you.
For large standing waves in an open canoe, put your bowman aft of the normal bow thwart position.
Both bow and stern should keep their blades in the water as braces.
When entering an eddy bow first, bowman must remember to lean into the direction of his turn to off-set the reverse eddy current.
In leaving an eddy, put your bow out first and lean DOWNSTREAM!!!
The water force on a swamped canoe is tremendous, and can easily crush you.
If you spill: swim for shore if the water below is dangerous. If you decide to ride it out, hold onto your canoe at the upstream end. Get on your back and float down feet first.
Become a student of water flow interpretation.
(The above, qualified of course, also applies to kayakers.)