All of your images suffer from either camera motion or focus errors. Also, exposures are all over the place.
If you decide to use exposure compensation, then you'll need to watch your histogram and turn on your highlight overexposure indicator (blinking highlights).
If you decide to use spot metering, there is no problem with that, as long as you are well-versed in using the zone system.
If you decide to use spot metering AND 2 stop overexposure (something I do 95% of the time), make sure you are metering highlights where you want to keep detail, and you use AE-Lock to keep the exposure setting until you snap the picture. The highlights will not be overexposed, and, in high contrast scenes the rest of the image will be underexposed. This is a great introduction to shooting raw, and how to best manage high-contrast scenes.
Focus issues are partly shallow depth of field, softness from using your lenses wide open, and possibly focusing modes in the camera. What works for me is to use Back Button Focus, where I turn off focusing with the shutter button, and designate a different button to focus on demand. In your camera you can use th AE-L/AF-L button to do this. But make sure you go into the menu and turn off AF Activation in the Custom Settings menu.
Shooting raw has another advantage - you can control noise and sharpening far better than you can when you let the camera do it.
This is an image from a D300, taken at ISO 1600 and cropped, which illustrates what an older, noisier camera with half the resolution is capable of:
_DSC1094 - sm by
Gene Lugo, on Flickr
Your camera can and should do much better.
All of your images suffer from either camera motio... (