Put them in the shade. Use a skylight or warming filter as the light in the shade will appear slightly blue on the pics (color film). You can also use a flash in the shade.
Or you can put them out in the sun with it somewhere behind them, and use a flash to eliminate contrasty shadows. The sun cannot be in front of them; they will squint awfully. The closer the sun is to the image frame, the more likely you will get flare. I try to arrange it so that I'm at 6:00, the people are at 12:00, and the sun is at 10:00 or 2:00 (but still behind them). Metering into the sun can be tricky with an in-camera meter. Meter the subjects close up to avoid the back lighting problems. Typical advice is to set flash to under expose one stop; this lowers shadow contrast but still looks natural. But other photogs I like even over expose one stop. So practice and see what you like.