Hey there,
I'm not usually in this section, but I thought I'd pull this tutorial together since I just edited a photo today. I'm nothing more than a hobbyist, but hopefully you'll enjoy this technique nevertheless. Below, you'll see a colored image that I took of the ocean in Adobe Lightroom 3.6.
Take notice of the flatness of the photo. Doesn't it seem a bit boring, a bit grey? It's also a bit blurry because of the low light quality I was taking the photo in (I should of increased my ISO to make up for that). Now, this might be my own personal preference, but I like my photos in strong color! It gives the photo power and intensity. If you don't see it, don't worry. You will in this next picture or two.
So now I'm going to switch it over into Black & White:
Gross. Look how grey it is in black and white. There aren't any absolute blacks or whites, just grey. Let's change that by increasing the black, contrast, and a few other variables to make up for the poor lighting and quality of my camera.
Woah! That looks a lot better. Now it has absolute blacks and whites, and the shadows aren't mid-grey. The sky is mid-grey, and the ocean has deeper tones, creating intensity - like the waves after the storm. If you don't see it, try comparing absolute blacks with the strongest blacks in the before picture.
So now let's bring it back into color:
Whoo hoo! Now that's a good picture (or the best I could get out of the best of a shoot of bad shots). Hopefully this has helped a little. I really don't do photography, so this is kinda my newbie workaround for editing color (I obviously work in Black & White mostly and have a better eye for Black & White photography).
Cheers,
Spirited
Edit: Sorry, I forgot to mention: If you notice the histogram, you'll see that before we were losing a lot of detail in white. You can tell by the huge spike at the far right end of the histogram. After bringing recovery and a few other things up, you'll see that the histogram has been shifted to the left (which brought back a lot of detail that was previously lost). Now, since I'm crushing the blacks in the final picture, you'll notice that the histogram in the final result takes a small spike at the left end. It indicates that a little detail was actually lost in the blacks, but that's the desired effect I had in mind. I think that's all I left off. The histogram is important to look at, so if you can when taking a bad picture that will need post-production, check the histogram for lost information (make sure there isn't too much or you won't be able to recover it - I was very close this time). Cheers.