How to take high resolution pictures?

I have a Nikon D3100 and I was wondering on how I can take pictures that are very clear, HD, and High Resolution. If any of you have a tumblr and seen some of the popular picture blogs with clear pictures, those are the types of pictures I'm talking about. Do I need photo editing software like PhotoShop? Here are some of the pictures I'm talking about:

You can go into the camera's menu and change the camera setting to sharpen the image and add contrast. Or you can just use the "vivid" setting. Of course you could use software to fine tune the sharpness and contrast.

If you need high resolution, you can change that in your menu as well. RAW (NEF) is the highest resolution. Or shoot JPG at the largest file size and least compression. I doubt you'll need this though unless you are making 16x20's from your files.