There are other techniques.....Use Manual take the reading from his face keeping shutter speed of suppose 1/250.....turn the aperture setting and where it is in between + or - sign, u can click the shutter.....The result will be almost same as my camera on A.P. read the face and exposed correctly at f6.3, which may perhaps be your aperture at Manual setting. ....In both ways there is an alternative......exposure compensation, towards + or - (minus)......On Manual setting come to exposure compensation mark and increase the aperture by one stop i.e. 5.6 and the picture will be more brightly lit. That is ur correct exposure. Still if u do not wish to alter the aperture, bring down the shutter speed at 1/125. You are getting the same result.....the best time is evening when u hv soft light and subject is against the sun.
As in case of Aperture priority I choose exposure compensation towards plus side, the picture will be rightly exposed if I set the aperture at f6.3.....In this case the aperture is stable and the compensation affected the shutter speed to give me a correct exposure, which may have come down to 1/100. .............................. In these cases still we feel that because of shadow of tree the details of man's face are not that much clear or visible, since his skin is dark
Now we come to our point of using a fill-in flash.........the example is given below. The camera flash did it work good.......There is no artificiality on his face as may be having some sunlight on his body, yea u can view his abs..........The moral is have a sharp eye, understand the exposure, and cleverly use the fill-in flash, bring out the finer details of the skin of person, animal, birds or anything u are exposing.....remember this small thing rather than being tensioned.