Portraits and highlights are not usually the ideal combination, however in the harsh brightness we get on the island of Malta, one can't really avoid it, especially when clients can only make their session during a particular time of day.
Practice has led me to still shoot in whichever conditions I am. It is all a matter of using light to your advantage and most importantly not get your clients to squint in the photos.
In the first photo, I have Penny posing just off a ray of bright sunlight. I exposed in such a way that I could recover my highlights decently, whilst still get my subject lit properly.
In the photo below I got my subjects to give their back to the light, and again I exposed in such a way that I could still recover the highlights in the woman's hair whilst still retaining good lighting on my clients.
My clients above were once again giving their back to the direct sunlight. So you can see that the most important thing is to expose well in order to retain detail in both shadows and especially in highlights. Not all cameras retain good detail in highlights or in the shadows, so knowing how to expose well with your own individual camera is of utmost importance. In the following examples, all shot with a Canon MK3, I underexposed by one stop, so that I could recover the highlight areas properly in post production, and be able to open the shadows without loosing detail in the highlighted part.
The portrait below was done as an example for my students. Nabia, posed for us in the shaded part, whilst her front part was lit up by the ray of sunshine. I shot one stop under, so that once again I could recover detail in the highlighted part and open the shadows to reveal Nabia's face.