Back-Lit. Potentially a scary photo situation, but also potential for artsy fun. I'm still in the experimental stages with back lighting; I can't yet predict how such photos will work out. I'm also learning how to compose pics that include flare. Flares happens when light hits the lens directly, and those circles of off-colored light appear in the pic. They essentially become another element to work into the composition. Most of the time one wants to avoid flare, and that's what the lens hood is for (as well as for lens protection from flying pinata sticks and tall people's elbows, and for making one's camera look more intimidatingly professional.)
The danger of course, is creating a photo of silhouettes - a totally different story. I may have used a pop of flash here so that we see some details, but also in these cases I'm angled so that the sun isn't directly behind the couple. Sunset light is best I think; the light is filtered through atmosphere, and thus isn't as harsh; is bright but has a faded quality to it.