Lighting

Luckily you don't need to drag round a full set of Profotos and car batteries to get this look, natural light is all you need. Shoot late in the day when the sun is low in the sky. This gives you a softer light, with natural fill, warmer colours and makes it easier to blow out (overexpose) the background and/or provide lots of highlights for great bokeh.

Shoot into the sun, or very close to the sun, paying attention to the way the light will be coming through the subjects hair.

Technique

Get close - don't crop. The shots in the "portfolio" section were not cropped in post. How do I know this? The depth of field. The use of a wideangle lens in this shot evident from the foreshortening (or lack thereof). As you go wider the hyperfocal distance (distance at which depth of field attains a maximum) gets closer. This means you have to focus even closer to avoid having everything in focus, which in turn means your subject has to be closer (to be in focus).

Cropping in post v.s. using a longer lens at the same aperture always increases depth of field. Shallow DOF is a big part of the look.

Equipment

Here's the bad news. I'm afraid f/4 on a 7D just isn't going to cut it, DOF wise. The image you posted was shot at 35mm f/1.8 on a full frame camera. To match the field of view and framing with an APS-C body you'll need a 22mm f/1.1 which is almost four stops wider than your 24-105 is capable of.

The closest you can get is a Sigma 20 f/1.8 which is over a stop slower and not great optically (compared to the 35 f/1.4L on full frame). I would actually recommend a Sigma 30 f/1.4 as it's designed for APS-C and is actually sharp. Or you could pick up a used 5D markI and 35 f/2 lens. Or you could keep your existing gear and develop your own style that doesn't revolve around shallow depth of field.

Processing

Nothing major here, can be done in camera or during RAW conversion. Basically you want a very warm colour balance, slight desaturation and don't correct for the lack of contrast you get by shooting into the sun.

Portfolios

A final advisory regarding viewing portfolios online. Anyone who shoots a lot of photos will come up with one amazing shot per year, regardless of their skill level. Apply this to a 20 year career and you get a portfolio of 20 outstanding shots. What you wont see is all the times the lighting was crap and the photos came out very mediocre. So don't lose heart of you can't get the results you want straight away!