Blinkies help in shade or tunnels, but are useless when in bright light. Reflectors might reflect the sun when it's low, but if the sun's blinding a motorist who's behind you, he won't see your front reflectors, and if the sun's blinding an oncoming motorist, he won't see your rear reflectors. Plus, they're designed for headlights, which you can't depend on people using during the day.

Bright lights in front and back, maybe even a xenon strobe (a powerful version of the blinkie) are your best bet for being noticed in the daytime, in addition to bright colors. A horn wouldn't hurt, too.