Outdoor Lighting

Definition: the main subject is between your camera and the major light source (e.g. the sun) such that your shadow falls behind you when you face the subject.
Best uses: to show edge details on your subject (e.g. hair, spines) or to show translucence (e.g. petals on a flower)
Example: Photographing tulips in the morning sun such that the tulip petals are between you and the sun rays.
How-To: You have two choices when the sun is behind your subject:

1) Keep detail in the rim-lit fur/feather outline, or to capture a silhouette
    => Dark backgrounds contrast rim-lighting best, so try to angle your shot such that your subject is in front of dark things
   => The best lighting for silhouettes usually happens at sunrise or sunset, in which case you should meter off the sky itself, but watch your autofocus as it may struggle with pure silhouettes
   => Otherwise, meter from the shaded side of the subject, and use exposure compensation of -1 or -2 stops; or try to use a spot meter off the rim of your subject where it's lit up

2) Show detail in the main subject and burn-out their outline
   => Try using a short burst of flash to illuminate your subject, or shoot on a cloudy day with the sun behind your subject
   => Meter off the middle of your subject, but definitely not off the rim where it's lit up
   => If you don't have a spot meter, then meter off the entire scene, but use exposure compensation set to +1 stops

Definition: a white, silver, or gold pice of fabric or material used to reflect diffuse light back onto a shadowed part of an object. Expensive polystyrene foldaway reflectors are convenient and light, but you can easily use a mirror or a piece of cardboard wrapped in aluminum foil. Fabric stores sell two-sided kite material with white on one side and dull silver on the other.
Best uses: to reveal more detail by reflecting light on the shadowed areas on your subject; silver and gold reflectors add some sparkle, while white is more natural
Example: Have a person modelling for a portrait shot hold a reflector on her lap such that the light decreases the shadow under her chin and reduces the wrinkles under her eyes.
How-To: Ensure there is enough light to reflect, and then place your reflector at an angle to light the shadowed areas of your subject; avoid putting the reflector too close to the subject or else it will look unnaturally bright

Definition: Camera Flash used with partial strength to light the shadowed areas in your frame; used to increase contrast.
Best uses: When natural light is not strong enough for a reflector, fill-in flash can be used in combination with a diffuser (e.g. piece of tissue paper placed over the flash) to reduce shadows in a scene.
Example: Brightening flowers in shadow.
How-To: For a soft flash effect, use a remote flash-gun with an off-camera cord. Align the diffuse material just outside the view of the camera lens, but twice as far from the flash as from the subject.

Definition: Harsh mid-day sun results in high-contrast scenes that are difficult for any camera to expose correctly. Dusk and dawn are the best times to shoot in direct sunlight, but shots taken directly in mid-day sunlight will turn out best if a diffuser is used. A diffuser is a piece of material that allows light to pass through it, but softens it - picture a flashlight pointed through a piece of white paper or a white bed sheet.
Best uses: To soften harsh light.
Example: Mid-day sun will cause your camera to overexpose the bright areas of your photo; to recude the contrast range your camera must detect, put a diffuser between the sun and the subject. This will increase detail and reduce contrast and texture. Same goes for the fill-in flash example above.
How-To: The further you place the diffuser from the subject, the softer the light will be. Use a translucent material to diffuse the light (not transparent, and not opaque, although opaque plastic can double as a diffuser) such as Rigid flyweight paper. Make sure your diffuse material is easy to hold in place between your light source and your subject.