Well first and foremost you will need lights, front and rear. I will not recommend a brand since that usually gets into a long debate but Im sure we can all agree on some lights.
Also when I am going to be riding at night I throw on a white long sleeve underarmor style shirt to keep me cooler and my helmet is also white as well. Just make sure to be cautious when riding as always and make sure you are in the bike lane. Other than that its pretty much the same as daytime riding just a lot cooler out