Stink is right. Composition is the key. You can make anything or anyone look interesting if you compose the shot right. And if you don't compose the shot well, then you can make the prettiest person or scene look naff.
As Stink also said, lighting is very important. Get the light on the subject right, then you don't have to bump the ISO up or widen the aperture so much. Even if your lens is capable of taking a shot in low light at f1.8, that's very wide and will give you a softer shot, which may not help. Also if you shoot at a f1.8 you need to sure that your focus is bang on, because your depth of field is so much shallower.
Even if you don't have studio lights, or your outdoors you can improve the light on the subject by turning them around to the light, or using a reflector or using off-camera flash to fill in the dark areas.