|It may be worth mentioning "light" in your case too.
I looked through a your entries, and your ISO is frequently at 1600. This will add noise to the image (though newer cameras do handle it better), which will in turn reduce the appearance of sharpeness. Any sharpening you do to a noisy image, will just be sharpening the noisy pixels. In general, I try to keep my ISO as low as possible while still achieving the shutter and aperture that I desire. Your shutter speeds are pretty slow due to this lack of light too, so you may be getting a wee bit of camera movement that translates itself as blur.
Since you only have a few entries, I'll list them out so you can have a look at your settings all in one place. In comparison, have a look at IreneM's camera settings. She's got some of the sharpest photos around.
ISO 800, Shutter 1/100
ISO 100, Shutter 1/250 <-- sharpest shot
ISO 1600, Shutter 1/4000 <-- That's just madness
ISO 1600, Shutter 1/30
ISO 100, Shutter 1/8
ISO 320, Shutter 1/60
ISO 1600, Shutter 1/25
ISO 400, Shutter 1/60
Lighting doesn't have to be anything fancy. Grab a table lamp with a white shade, and put it as close to your subject as you can without getting it in the frame. Adjust the distance if there's too much light.