The Shade is your friend.
This is probably going to be the simplest tip ever. Don't shoot people in bright sunlight. You will invariably get plasticy skin and very deep black shadows all over the place, courtesy of our nice, strong sun.
All you need to do is to walk your friend to the nearest spot of shade and voila - instant beauty. Do keep inmind that both your subject and your background must be shaded, if you put your subject in the shade but behind him is roasted in sunlight then the camera's sensor will be overwhelmed.
The left image is shot in the shade of a nearby building, whereas the image on the right is not in direct sunlight
If you *HAVE* to have sun-roasted background in the shot (for example because it's a tourist attraction you want a photo with) then asking your subject to wear sunglasses will minimise the worst areas of shadow (the eyes).
Camera Sensor
Whatever the camera you are using, there are some physical details that you should be aware of that will make your life easier. Lets start off with the sensor - as you all know, this little bit of electronics is what replaces the film in a traditional camera. The key thing to be aware of here is the size of the sensor and simply put - big cameras like professional dSLRs have bigger sensors (conversely mobile phones have small sensors to fit in their slim body).
The size of the sensor means that the camera is able to capture more light for every photo you take. This means that smaller sensors work best when there is lots of light (for example in the middle of the day) whereas bigger sensors are able to work in darker conditions. Larger sensors are typically better at getting rich, natural colours.
What does this mean to me? When buying a camera or a mobile phone, the sensor size is not always advertised but on sites like www.gsmarena.com or www.dpreview.com you can find this detail. Larger sensors typically translate to better light handling, especially in the evening.