There are 2 main possibilities why a pic is not sharp (assuming that the focusing is spot on, it is a reputated sharp lens, e.g. macro lenses, and that the lens has no front or back focusing issues, proper lighting, etc.).
1. Handshake --> practice handholding techniques, use tripod/monopod
2. Subject moved --> use faster shutter speed
Also, because this is a digital camera, the number of megapixels you shoot at can also affect the "sharpness". When you use more MP to capture a pic, it becomes more sensitive to movement... and when you zoom in, you can see blur (for pixel-peepers).
For your pics, the following information were retrieved from the EXIF (all shot in Aperture mode).
a. Old woman - 1/80s, f/13, ISO200
b. Indian tourist - 1/400, f/10, ISO200
c. Totem pole - 1/250, f/10, ISO200
Generally, I find the pictures sharp enough. Even for the "Old woman" pic, it is sharp enough. Look at other parts of the pic, like the umbrella, and you can see it is sharp. The possibilities is that she is under a hat and lighting becomes a possible issue. When there is insufficient lighting, the subject tends to be not as defined. So, you can use your lens with aperture wide open, and this would increase your shutter speed. I like to shoot portraits at about 1/250s to make sure I take care of handshake or subject moving. When you shoot moving and active children, you may even need to use up to 1/500s if you want to freeze their movements. If you want to maintain current settings, try using a flash to light the woman's face. You are also using matrix metering which evaluates the whole scene. If your primary theme of your pic is the woman's face, then change your metering to spot or center-weighted and meter at her face.
Can I suggest that you try to shoot your pics with aperture wide open. I believe this is a 18-55 f/3.5-5.6 lens, so use the maximum aperture possible. Change your metering mode to spot or center weighted. If your method of shooting is focus+meter then shift to frame the pic, then make sure you lock the metering at the spot you want (go into your menu and change your option to a full menu, and you can see the options of how you want to use yoru AE-L/AF-L button). Try this out and see how it goes