I'm no expert, but from what I have picked up or tried myself, using a combination of shooting in RAW and understanding layers in Photoshop there are very few problems that can't be solved "later" when you are on the computer.
Cameras see as their sensors or films see - and that is not necessarily what the human eye sees. Our eyes and mind are constantly processing the images in real-time, while the camera only reacts to the photons hitting the sensitized surface of the medium. RAW (and/or brackets) and layers are so far the best way to reconcile unrealistic camera images with what matches what your eye saw and soul felt, when you made the exposure.
Using image processing in this way is not covering your mistakes or "cheating", but rather using your skills as a photographer to present an honest interpretation of the image to the viewer. You are not compensating for your own weaknesses, but rather for the limitations of the medium. In photography since Henry Fox Talbot made the first viable negative/positive print in 1836 to the present moment, it has always been thus.
Even if one is mostly working with JPEGs now, please shoot RAW+JPEG if the camera supports it. When I first shot RAW nearly a decade back, I was totally unimpressed. It was not a problem with RAW but with a combination of immature software and my lack of understanding of the potential richness of the format. I shot RAW far less often than I should have.
With years of subsequent experience and understanding, I have been revisiting the early RAW exposures with Photoshop CS5 and drawing image quality out of them I could not even guessed existed within them when first exposed. Alas, if only I could roll back the years and have had the foresight to have shot them all as RAW. RAW contains data representing the state-of-the-art that your camera can capture. Even if you can not fully utilize it at the moment, the time will come that you can and you will be grateful for having done so. For the sake of the future - shoot RAW.
Bracketing shouldn't be necessary when you can use the RAW file to create (say) three versions at different exposures. Admittedly that is more effort, but it cuts down on memory card usage and (I think) shutter speed time in the field.
It all depends upon the dynamic range with which you are dealing, and the answer is always there if your camera can display a histogram. If the graph is piled up against both the right and left vertical axes, you know that you have exceeded the camera's ability to capture the whole dynamic range. At that point, bracket and either use layers and masks or HDR to capture the full range of detail in the final photograph as you process it.
Storage has dropped in price dramatically from my first 64MB card to my present 8GB card, so I don't sweat it. (The 64MB card was over $200Cdn, and one can find 8GB cards for around $20 now, with 8GB cards that can handles the extreme write-speed of my current camera for $60!) We live in wondrous times.
If I bracket for HDR I let the camera shoot all nine exposures at full stop intervals. Once in Adobe Bridge or PhotoMatix, I choose the range that will provide the highest quality image. Much easier to use five out of nine, than to realize you need a couple of brighter or darker exposures and go back half-way across the world to get them. It gives one the option of trying combinations until the very best image quality is achieved.
Similarly ND Grads - layers could be used to replicate the effect, I think? I only have the circular ND Grads which force the division to be halfway up the picture, which isn't going to be right usually.
One can always spot a TV documentary from the late 1970s by the terrible, unrealistic ND grad that every cinématographer thought was the solution to overly bright sky. The filters take exactly the right subject matter and incredible skill to use realistically. However, at the time, they were the only viable solution.
With layers and masks, Adobe Camera RAW (ACR) lets you deal with individual problems within the image - high-contrast sky with low contrast earth, mixed light sources, whatever. In the full version of Photoshop, there is an HSL tab in ACR. Using the blue sliders, one can recover every bit of blue sky that may have been captured in the exposure, and one can even simulate the effect of a polaroid filter, even if one is pointing the lens at 90° to where an actual polariod would work.
What I read somewhere is that you should deliberately overexpose, because it is easier to adjust exposure downwards in PS to bring the detail in the highlights back, but if you underexpose, the dark areas cannot always be adjusted to bring up the detail.
That is as wrong as saying the opposite - that you should do whatever is necessary to protect
all highlights. Reflections off chrome trim in full sunlight have no detail whatever, and only look natural if they are pure white - don't sweat it. However, when the white of a building or cloud exceeds the film or sensor's capability of recording it, it is gone - totally - and forever. The key is to expose to protect SIGNIFICANT highlights. Where it is right on the edge, Adobe Camera RAW has a slider called Recover. It can pull the highlights down somewhat with little impact on mid-tones, but it can not recover that which has been totally lost to overexposure.
Ideal exposure shows a histogram where the graph is just barely touching each axis. That guarantees at least a touch of pure black and a touch of pure white which makes the image sparkle in its full dynamic range. There are exceptions, but in general terms one wants the full range. Without a pure white, the image can look dark and muddy. Without a pure black, the image can look weak and washed out. A low dynamic range image is easily stretched in processing. A high-dynamic range image is very difficult to recover to the point of producing acceptable image quality.
The Brightness slider in ACR is a sophisticated version of the traditional gamma or mid-tone adjustment. It leaves pure black and pure white intact, while adjusting the curve of the lightness values in between. By moving it right or left, one can reveal the maximum shadow or highlight detail in a normal dynamic range exposure. ACR allows even finer tuning with the Recovery and Fill light sliders. With care and skill, one can come very close to honestly duplicating what one saw in ones mind at the time the exposure was made.
