I came across a nice photoshop lesson on how to sharpen your images. I didn't really understand the power that sharpening does until I took Scott Kelby's photoshop class at the Jacob Javits Center a few years ago.
Scott went into great detail on how he uses Camera Raw to finish his sharpening and I have been doing it ever since. I actually make 70% of my changes in Camera Raw
It makes a big difference when you have your images printed. This is the main reason why some photographers are not happy with the print services they use. This is the main reason why I stick with SmugMug doing my printing. I use them and I also use MPix on occasion as their pictures actually print the way they look on the computer screen.
If you have ever gotten back one of your prints and it is very grainy it is probably a combination of the sharpening done on the photo and the printing service.
This 4 minute video will change your workflow if you have not added image sharpening to it yet.