Often when I take pictures they turn out much darker than I would like. My camera also tends to take very "cold" pictures, and that is probably because I always use the auto white balance setting. I can only do so much with the equipment I have. I set the aperture as low as I can so that I can let in as much light as possible, and I like to have the ISO as low as possible so that the pictures are not grainy. I take the best pictures that I can with in the situation I am in, and the rest I leave up to Photoshop. I normally have to lighten my pictures, "warm" them up so they aren't so blue, and I usually bump up the contrast just a bit. I like the colors to be rich and vibrant. Sometimes I sharpen parts of the picture, like the eyes of a person, or something I want to stand out. Sometimes I sharpen the whole picture. My point in all of this is that I ALWAYS process my photos. Just look at the difference in these shots of my nephew.
All I did in these pictures is lighten them (using the curves function in Photoshop), warmed them up using my favorite free action from Pioneer Woman, and then bumped up the contrast just a tad. Oh, I also lightened and sharpened his eyes just a bit (to do that I used two more free actions from the Pioneer Woman). They were pretty simple changes that hardly took me any time, but yielded MUCH better results. Perhaps as my skills improve I will take even better "Before" shots. For now I'm just grateful for Photoshop!
Hope you enjoyed my example of how much a few simple changes in Photoshop can help make pictures better :)