If this is what they want then you could do this pretty easy. Its just photos with natural light in late afternoon with the aperture set probably to f2.8.
Couple pieces of advice when working with models.....
1) Start from the head down.
Figure out what side of the face is the good side and if they have a face that you could shoot facing directly forward. Also examine right and left profile. Then once you make these decisions work on poses that will feature that side and what kind of directional lighting you will need to get the right kind of shadows.
2) Clothes are KEY!!!!!
A bad outfit equals a bad shoot. Make sure they have good clothes to wear and dont show up in just a ratty t-shirt and jeans unless that is the idea to begin with. But clothing is not something you should find out about last minute. You need to do this before you even go out on location.
3) Focus!
Get it right the first time. If possible use a tripod to ensure steady in focus shots. Or at least be very critical about holding the camera as steady as possible. When people are out of focus even slightly the whole shot can be garbage.
4) Location
Have a general idea of where you want to go and things you may want to use as background. Try an area that may have a few options like a nice park close to where you may also find graffiti. Then you can try out a couple setting and see which one the shoot takes to best.
5) post processing
Be consistent. You want the set to have a cohesive feel and look like it belongs together in the end. The tones are an easy way to bring different locations together.
And most importantly - NO DEAD ARMS!!!!!!!
Nothing ruins a nice modeled pose then a lifeless dead arm hanging there with nothing to do. Keep it bent somehow.
This is the only fashion shoot I have ever done. But my model knew what she was doing for the most part. So you may be able to use some of the shots for ideas on posing at least.
http://www.flickr.com/photos/diskojoe/sets/72157626730393534/