My wife recently got a D3100 and has no idea how to use it, nor do I. What is the best setting for picture clarity/quality for normal 4x6 and 5x7 pictures. Any help would be greatly appreciated. Thanks.
Mark has given some good advice, using Auto or "P" as initial shooting modes.
I would add that I would set:
Size - largest setting (full 14 megapixels, it's what we paid for), regardless of the size of the anticipated final print.
Quality - "JPEG Fine" which is the least compression. You can shoot NEFs later when you have more experience/knowledge.
Picture Control - Standard or Vivid (more color saturation and contrast), whichever you prefer. I like Standard for people shots because there is less saturation of skin colors, I like Vivid for everything else.
White Balance - Auto
These settings should get you started. Like all of us, you'll learn as you shoot and will have fun tweaking the settings to see how they affect the results. You'll soon be setting up your D3100 for your individual needs.
Nikon user for 40 years. F-Ftn, F3, F4S, F90, F100, D5100, D700