In which mode, from what angle is it best to shoot?

Basically I want to create dreamy looking photos
(like those of Anastasia Volkova / link: )
I've read a lot and learned that a 50-mm lens is best for this style. Right now I can't get a 50-mm lens so I have to work with my 18-105 mm one and Nikon d5100.
Any tips?
AND also, I want to create a lens flare, or just place my object so the sun is behind them (meaning my camera is facing the sun) what mode, angle is best to shoot with so my object doesn't turn into a faceless silhouette?

Why on earth would you want flare in your pictures?

Shoot at the telephoto end of your zoom range with the largest aperture available (which, @ 105mm, is 5.6)

"… What mode, angle is best to shoot with so my object doesn't turn into a faceless silhouette?" You need to meter on the subject's face and use fill-light.

To get shots anything like hers you need a fast lens, something with a maximum aperture of at least f/2.8. Shoot with the sun off at an angle so you are not totally backlighting your subject and use a reflector to add light to the subject's front. Shoot in aperture priority (or manual) with the lens wide open and spot meter off your subject to get the exposure on the face dead on.