Question: I've noticed a lot of my pictures look muddy. They don't have very high contrast. I know I can post process some pictures, but what is the secret to having nice contrast in a picture?![alt text](https://i.stack.imgur.com/aDZWC.jpg)

Answer: 
Can you post an example? (even a text link to an image hosted elsewhere)

Here are a few common solutions:

1. Adjust the levels in photoshop or some other tool, using either auto-levels, or just manually pull the whitepoint down to the top of the histogram and the black point up to the bottom (for example: <http://www.cambridgeincolour.com/tutorials/levels.htm>)
2. Local contrast enhancement: Use unsharp mask, amount: 10%, radius: 200pixels, threshold: 0 (for example: <http://www.luminous-landscape.com/tutorials/contrast-enhancement.shtml>)

Aside from what you can do in post, I'd suggest look at the lighting you're taking pictures in. Try taking pictures using window-light only, or on a cloudy day. Avoid bright sunny days. Colors really stand out on cloudy days I find.
* Are you using flash? Pictures with harsh flash tend have a washed out look, with dark harsh shadows.
* In my experience non-SLRs (Point and Shoot / pocket cameras) get terrible results in-doors without a flash, even in situations that seem well lit to the human eye. Photos may look waxy from too much noise reduction (which is necessary in low light to get a steady shot, hand-held).
* A lot of the time the secret is to have good lighting in the first place. Sometimes a subject just won't look good no matter how good your camera is or how you set your camera settings, if the lighting is too harsh and shadowy. This can also happen in bright daylight, for example. The shadows show up black and the bright parts overexpose--- the camera may not be able to handle the dynamic range.