Headlights are important, but tail lights are more so. Get a bright strobing or flashing tail light, mount it on your bike, then walk back 100 yards and see what you'll look like. You want enough power to be obvious.

Then it's a mater of getting out there and adjusting your vision to the light level. Start on a few simple rides around your neighborhood, and when you gain confidence branch out farther, until you're comfortable in the dark.

If it helps, based of 40+ years, I've come to the conclusion that a well lit bike stands out more and is more obvious to drivers in the dark, than even riding in the daytime.