I use an LED deck-mounted (suction cup) light right behind me. (Where it doesn't interfere with my night vision). Mine is made by Paddlers Supply. It stands 8 or 10 inches above the deck and is exceptionally bright- can be seen for quite a distance.
For a headlamp I use a waterproof one from Underwater Kinetics. A bit bulky, but truly waterproof and bright.
I also have SOLAS reflective tape mounted around the cockpit and on the paddle. It works incredibly well.