Hani,
Image sharpness relies on a variety of things. There isn't one list of settings that are going to give you the sharpest images under all conditions.
In general, where possible you want faster shutter speeds. This helps eliminate camera shake and motion blur caused by motion of the subject. However as you increase shutter speed you'll also need to increase your ISO to achieve a proper exposure.
Once the ISO increases beyond a certain point (depending on your camera and the size of your sensor) you'll start to see visible noise in the final picture. You can use software to reduce this noise, however that will also impact the sharpness of the photo. So it's really a balancing act between the two settings.
The same can be said of aperture. As you increase aperture (reduce the amount of light coming into the lens) you gain DOF - depth of field. Which means more elements in the photo will appear sharp. However it also means you'll be reducing the amount of light coming into the sensor, so again you will need to either lower your shutter speed or increase your ISO to get proper exposure. Lower your shutter speed too much, you'll introduce camera shake and possibly motion blur. Increase your ISO too much, noise.
In general getting good sharp photos requires you to balance these settings properly depending on the amount of light available. I'd recommend you do some reading about the exposure triangle and practice balancing these settings to achieve the best possible results.
Their are other factors involved of course, once you master the exposure triangle it would be a good idea to do some reading about your camera's autofocus system. Find out how and why your camera decides what to focus on, and if possible how to control or at least influence that choice to get the kind of results you want.