If you want portraits to have that dreamy look, use a lens with a wide aperture (a small F-number, like 2.8).
I took this picture yesterday, using a prime 35mm lens (the Canon 35mm f/1.4L) on a Canon 7D, at an aperture of f/2.5 and a shutter speed of 1/50th second.
That 35mm on a 1.6 crop factor camera is like 50mm on a traditional full frame camera. So it’s a “Nifty Fifty”.
A that focal length, I was able to go quite close to Mr Pumpkin without much distortion, as you can see.
That gives you a very nice look. The close proximity combined with the f/2.5 aperture gives me nice soft bokeh (the creamy quality of the background blur). Even the back of the head is soft.
Beautiful: reason for a smile.