Is the photoshoot outside?
If so, make sure it's on a sunny day. Also, do it when the sun is not directly in front of you, so in the range of 1-5 PM.
Avoid shadows in face and all, by orienting yourself properly with respect to the sun. Do not use a flash. It will pretty much always overexpose your photos. If you really need it to fill out a bit, you can orient the flash so that it bounces on a white shirt or something, but not directly on the person (without a diffuser of course)
I usually try to max my bokeh effect by using large apertures, if you have a distant background and wanna isolate the subject.
Try out with angles. Try with different apertures. Have some fun with shutter speeds and jumps. Some shots against the sun can be awesome too (shadow people). I find the 85mm f/1.8 a great lens for shoulder/head portraits, with very pleasing bokeh. The 50mm f/1.8 produces very good and crisp results too. They are both inexpensive and produce results much more worth their price imo. Use ISO 100 for outdoors, but you might find yourself needing ISO 200 for making shadows less harsher in some shots.
If it's inside, boost your ISO (800-1200 maybe) and use flash if needed, but it's much harder and I'm not that experienced for that yet.

Hope that helped!