Night riding is as "safe" as you make it. I ride year-round in a wide variety of conditions. Night riding is not a big deal, I ride slower and I will avoid busier roads that I would ride in the daytime. You have a lot of advice about lights, reflective gear, etc. Here's a couple pointers based on my experience:

If you're biking on roads with traffic, have a light bright enough to standout with the cars' headlights/taillights.

Make sure your batteries are charged (relates to the above point) - I hate to say how many times I see a rider at night with lights but the batteries are clearly drained.

Many people advise using a strobing light, do me a favor, try looking at that light strobing before you use it on the road. They can be blinding, and that doesn't help. My NiteRider 700 has a strobe function I have never used, 'cause that thing is blinding! In fact, I won't use 700 setting when I'm on the road with cars, it's like highbeams.

To the point above, be attentive to where the light is pointed - it should be on the road ahead of you (30 to 50 ft); not in everybody's eyes.

Like others have stated, a helmet light in addition to handlebar mounted light is very helpful. Helmet light allows you to direct a beam of light to see the conditions in a turn and at specific drivers to get their attention. I prefer a low-powered helmet light with my NiteRider on the bars.

Spoke lights really help with visibility to cross traffic. I like this - SL-LD120 | CATEYE

And/or reflectors - Amazon.com : Lightweights Power Reflectors for Wheels (86-Piece) : Bike Lighting Parts And Accessories : Sports & Outdoors - I have these on most of the bikes in my house, but none quite as 'bright' as the examples.

Take some night rides on quiet roads or trails and get a feel for your comfort level before working up to busier roads.

Hope this helps.