When you're on a trip, you'll probably want to shoot portraits with local landscapes in the background. When you do, pay attention to lighting. You can't choose where the light is coming from; instead, you'll have to adjust your technique to the available light. If the light is coming from in front of your subject (direct lighting), the camera may assume that the subject is too bright, resulting in an underexposed photograph. This can be prevented using exposure compensation. Adjust exposure compensation upward until you reach the desired exposure.
If your subjects are backlit (i.e., they are brightly lit from behind) or if your subjects are dark while the background is brightly lit, their faces may be in shadow. This can be corrected by using the built-in flash. The flash produces lighting that balances the brightness of the background.