These tips aren't really for seasoned online scrappers...they're more for anyone who is newer to sharing online or has had trouble figuring out how to get better photos of their projects.
One of the most important things you'll need for a clear photo is good lighting. Natural sunlight is best if possible. I've heard Ott lights are the next best thing, but can be rather expensive. :-D If neither is an option, use the best lighting you can get in your home.
Most people either place their project flat on the floor or a low table and take the picture from directly above (being careful not to block the light source), but you can also stand it up directly in front of you.
When taking your picture, turn off the flash and square your card or layout in the viewfinder or on the screen by making sure that all 4 sides are parallel to the sides, top and bottom in your viewfinder/screen.
Next, you can use software that came with your computer or camera if you do not have photoshop (you'll need to see what editing options are available for your individual program), but there are also free online options to crop and enhance your photos. Gimp is similar to photoshop and available for free to download. Photobucket also has some really cool photo editing options. You can use any of these to correct any lens distortion if you find that your images end up curling in on the corners even though your project isn't like that. You can also adjust the brightness and contrast to make your image less washed out or dark, etc if necessary and crop the distracting background out of your photo so that all you see is your gorgeous layout or project.
Anyone else with help hints/tips, please feel free to share in this thread!