I have a couple that wants their picture taken from a hillside in Lake Tahoe. Great! However, they want the lake in the background. I know from the past I have either made it to where the people are black or the background is white when the background is bright. How do I take a good picture where both the subject and background are perfect??
Absolutely use fill flash, but also try to make sure that the sunlight is shining on their faces, maybe a bit from the side. That way, the same light will be on their faces and on the lake.
It's not so much of an issue if the sun's mostly behind you and lighting their faces. But if you shoot with them backlit or from high overhead you'll need fill-flash, or maybe some reflectors, or to use one of the listed "tricks" in post-processing.