Think about what to include and exclude when composing. Most people are good at including, but the important part is what to exclude.
Think about your position, aperture, shutter, film speed, etc
Capturing an Image
Research the site and try to only bring the equipment you need.
Shoot RAW to maintain data.
Rule of thirds.
Light
Looks totally different from every angle, so move around to get the best light results for the effect you are looking for.
Use your hand as your "free" light meter.
An eye is much more sensitive than a camera, so squint your eyes to better approximate what the camera sees.
Hard, unfiltered vs soft, diffused.
Try to use natural light as opposed to flash.
Go off the automatic settings, but auto-focus is fine, usually.
ISO
Low ISO -----> sharp : High ISO -----> grainy
SLRs do much better at high ISO as compared to the point-and-shoot.
Shutter Speed
How steady you are able to hold your camera, and the movement of the subject are both important important when choosing shutter speed.
Slow = Blur : Fast = Freeze
A tripod recommended at slow shutter speeds.
Try using walls, pillars, your elbows, and other objects to steady your hold.
1/4 of a second is about the slowest for hand-held shots.
The goal is 1/125 - stops a bicycle — 1/500 stops the rotor blades of a helicopter.
Try for 1/60 to 1/125
Bracketing - use several settings for both F settings and shutter speeds to find the best results. Some cameras have an auto-bracketing feature.
Going down (increasing F number) by one stop, shutter speed decreases by one setting.
F number goes up (less light) , shutter speed goes down (more light).
Sunny 16 rule - F16, use a shutter speed of the reciprocal of the ISO setting.
Wide shots.
High aperture to give a full DOF (Depth of Field).
Wide angles makes what is closest to the lens look bigger than what is at a distance. Close shrubs as compared to distant mountains.
Mid shots
Action shots
When shooting a moving subject that requires you to swing to track the subject before shooting, place your feet in such a position that you will not be twisted at the waist at the end of the swing when you need to be steady while making the photograph.
Close-up
Change lenses to compensate when you can't move.
If you have to choose between under, or over-exposing, choose under-exposing to make post processing more effective. RAW is important for this.
Don't look through a camera as you would through a rifle scope. i.e. you often won't want your main subject to be in the centre of the frame (bullseye). Related to rule of thirds.
Photography speak to your subjects: Don't "shoot" or "take" (aggressive in some countries), but "make" a photograph.
Perspective lines - lines (like a fence, telephone or power lines, and road markings) that come out of the corner of a frame focus the eye on the centre of the image.
Change the perspective by kneeling, moving up, down, left, or right.
Avoid using the zoom - move closer if you can. Moving closer to the subject may be more effective than using zoom.
Choosing Lenses and Using a Lens
Choose the lens for the effect.
Wide angle less emphasises the foreground and makes the close subject/objects look bigger than they actually are.
The most important thing to know about a lens is how to work with compression factor/perspective with the camera settings.
For portraits, use 50 mm or up, preferably 85 mm.
If you can afford an F2.8 lens, get it.
Image stabilized lenses have 2 settings - setting 2 is for panning; i.e., it only stabilizes vertical movement.
Scope out the Scene
Think about the sun - where will it rise compared to where you can/could be located?
Think about the background.
Use DOF to emphasise or de-emphasise the background.
Lighting
Angle of the light is crucially important.
Sharp facial features - light from above.
Chubby face - from the side.
Never light a face from below, unless you want them to look scary.