Before taking the picture there are five things to consider…

Composition:

Llook at the background check for plants trees lamps growing out of the subjects head. Choose a background that is plain and not busy, unless you want an environmental portrait showing the situation, a castle or garden.

Lighting:

Ideally the light should come from the side at 45deg and 45deg down. The best light is natural light through a window,  avoid  direct bright sunlight, north facing windows are best, the light is much softer and consistent and will not cause the subject to squint. If you want to take a picture outside avoid bright open spaces the light will be harsh, one side will be bright and the other dark. Another problem is Panda eyes because light is coming down causing shadows in the eye sockets and under the nose and chin. Take out the toplight by going under a tree or under a canopy, the light will then come more from the side and show the eyes without shadows. If you are taking a group, find a shadow area in front of a wall or large tree or hedge and have the sun behind the group again this avoids people squinting. If the weather is overcast most of the problems disappear.

Expression:

 The main aim is to get the subject relaxed and comfortable some of the best portraits do not look straight at the camera. Talk to the subject, tell a joke, do something silly. Get the subject to enjoy the session and want to be in the picture.

Pose:

 Avoid taking the subject straight on, turn the body, it will look slimmer, avoid straight arms try to bend knees. Watch for tense hands showing knuckles or hands hidden by jackets or shirts. Lean against a wall or pillar, rest your arms on a wall, sit on steps or a block of some description.

Space:

Leave space around the picture so that it can be cropped to produce an even better picture to go in a frame.
Above all concentrate on the eyes they should be sharp and happy. Expression, expression, expression.

Good luck,
Andris.