While composition is a fundamental element to a good image, without good exposure the quality of the image will be weakened. To ensure proper exposure one should correctly meter shots.
When out and about, one should use in-camera metering. More on this, and the correct interpretation of histograms in a future post.
When using strobes a good incident measurement device should be used. I use the Sekonic L-358 FlashMaster. It is a very effective mid range meter. More on effectively using light meters in a future post.
Light colour is the next most important light measure. Most digital camera have white balance settings that approximate the lighting conditions. However light colour is influenced by many factors e.g. dominantly colours in the surrounding, different light types etc. These demand that extra care be taken to measure light quality which starts with using a 18% grey card.
To effectively measure light colour and create a camera profile I use the X-rite ColoChecker Passport.
Finally, with the image correctly exposed and the light colour measured, we need to ensure that the monitors on which we process our images are correctly calibrated to emulate true colours. I use Spyder Pro 3 to calibrate both PC and Mac monitors.