Advice on portrait photography
Depth of field
The most important effect you'll want to create in a portrait photo is making the person appear sharp and the background blurry. You can create this effect with a small depth of field. Because of the large difference between the sharp foreground and the blurry background, the person appears to pop out. In order to achieve this affect, you'll need a lens with a large aperture. Think of a lens with an f-number of, for example, 2.8.
Looking at the focal length, there are many lenses you can use for portrait photography. It's mostly about how far you are from the person. A lens with a fixed focus doesn't zoom, meaning you'll need to decide the distance between yourself and the person. The shorter your lens's focal length, the closer you'll need to be to your subject. If you go for a variable focal length, you'll be able to zoom in and out and decide what kind of photo you want to take.
Image stabilization in your lens is not a luxury. It prevents motion blur caused by vibrations. It's very handy when you're holding the camera while photographing. Image stabilization is even more handy when photographing in low-light circumstances. Think of portrait photos you might take at pictures. In that case, you should work with slow shutter speeds, allowing as much light as possible to fall through the lens and onto the sensor. Slow shutter speeds increase the chance of motion blur in your recordings.
Portrait photography is a matter of experimenting with composition a lot. A good vantage point ensures a striking photo. A photo where your subject is exactly in the center can get boring quickly. Why not put your subject left or right of the center. Choose a low or a high vantage point. In the end, it's you who decides what you like.
Eyes are the mirror of the soul. It may be a clichéd expression, but it does apply to portrait photography. When taking a portrait photo, you'll want to focus on the nearest eye. A golden tip: a good portrait photo lets you make eye contact with the subject.