a zoom lens of 18-105mm f/3.5-5.6 will be a great start (It's 24-105mm f/4 for Canon). At the 85-105mm setting, you get to shoot nice portraits from a comfortable shooting distance. At relatively wide f-stops (f4.5 and 5.6), you can get a sharp shot of the subject while blurring the background. At 18-50mm settings, using relatively small f-stops (f8 and f/11) you can get an entire scene in focus for environmental portraits or landscape photos. You can do a lot with this one single lens! Hope this helps!