Shoot right to begin with !
Digital photography is so adaptable and flexible that many new photographers start thinking they do not really have to worry much about exposure when taking photos because they can “fix it later in Photoshop.” This very thought can get you into trouble, leading you not to actually learn the fine nuances of photography.
Underexposure can cause problems with colour in dark areas, as well as dramatically increase noise, no matter what camera you use. Even if you are using a very good camera known for its excellent performance in low light, it will definitely perform better in good light in comparison. So, increase ISO only if there is no other choice. Overexposure can result in highlights as detail-less white areas that can never be recovered. The highlight alert on you camera lets you know if any important area is getting washed out. The washed out area starts blinking and you can make this out in bright outdoor light. While getting the correct exposure is important, you can get away with being absolutely correct and leave slight fine tuning for the camera's RAW convertor.
The wrong shutter speed will cause sharpness problems from camera movement during exposure to blurred subjects. This is something which simply can be taken care of in Photoshop or any other software. So, no out of focus or Blurred images to begin with.
An incorrect white balance can create colour cast problems, but this can again be fine tuned as you go through your images on a large computer monitor.
You do not have to be a pro to shoot your images correctly from the start. Simply know your camera controls and be sure to make the right usage of them. This requires that you know your camera thoroughly well. Fine tuning later is fine but not if you just need to rescue your images later from bad exposure or white balance.
Although image-processing software provides you with tremendous image-adjustment power, you can always do more with well-crafted photos than you can with marginally acceptable ones. You spend less time working on an image in the computer if you have an excellent or close to excellent image to begin with.
You can use any camera to quickly adjust exposure without using any dials. Point your camera at something dark, lock exposure (usually by pressing the shutter halfway), and then move the camera back to the composition in order to add exposure. Do the same with something bright to darken exposure. You do need to be careful of distances here because locking exposure on many cameras also locks focus. The “something,” bright or dark, can be at a different distance from the camera than the subject, which would cause sharpness problems. Or simply point the camera to something grey or neutral to ensure the exposure is correct before locking it. On the other hand, moving dials becomes quite a reflex action and when shooting on aperture priority simply move the exposure compensation dial towards "Plus" to addd exposure (add more light ) and towards "minus" to reduce exposure. ( reduce light )
Once you have your DSLR, get a good-sized memory card (prices are very reasonable now). If you do not shoot on burst mode, do not spend too much money on a very high speed card, rather get more capacity. The relatively slower cards today are also fast enough for regular photography. Taking photos costs nothing, so move out and shoot as much as you can, however not random photos but keeping in mind that you aim to get a good photograph every time you release the shutter. This is the best way to become a better photographer. Try different exposure settings and compositions, compare them in the LCD, and shoot plenty of photos so that you have a choice among them. Give more attention to composition than exposure as aesthetics is always more important than the technicalities. Exposure can still be taken care of but nothing can change the content of the photograph.