Safety comes first: Practice caution when shooting into the sun since the sun can burn your camera sensor and/or cause eye-damage if allowed through the lens for long durations (more than a few seconds).
Use a small aperture: A small aperture reduce the size of light source and helps avoid blowing the highlights. A small aperture gives you the starlight effect which shows up beautifully against the subject.
Use Sun Flares: While sun flares are avoided most of the times, creative use of sun flares can render a dreamy look to the entire scene especially the portraits.
Strong artificial light: A smaller aperture necessitates the use of extra lights. This helps compensate for the low light, to control the shadows and also to reduce the contrast in the entire scene.
Shoot in the magic light: It is always recommended to shoot in the soft, angular light of the sunrise or sunset rather than the harsh, bright light of the afternoon sun. Also shooting during the main part of the day can pose limitations to the composition and perspective since the sun is high up in the sky. Magic light (when sunrise /sunset) is one of the best time to shoot against the sun.
Use of GND filter: Use a GND (Graduated Neutral Density) filter which allows you to tone down brighter areas of the composition and help balance the overall light in the scene.
Use of Light Meter: The old adage “prevention is better than cure” fits this scenario. You can’t compensate or correct bad light during post-processing. So measure and correct the light during the shoot.
Use of Reflector: Use a reflector to avoid underexposing the main subject and reflect some light on the face of the subject to control the shadows.
Post-processing: Last but not the least, feel free to toy around with the image during the post-production to fine-tune the desired effect. With the new image editors the possibilities are countless.