Before you take a shot, have your ISO base settings in order. The lowest value will always leave the highest quality images. The reverse is true.
Using a small aperture increases the depth of field. However, it also increases the diffraction effects. This diffraction hinders the focus on the sensor of the camera resulting in a softened image, which is blurred.
For one to take professionally sharp images; light is a key factor to consider. You have to think about the type of light you are working with; is it subdued or vivid or maybe something in between?
While it may be challenging to have perfect images, there are several things you can do to sharpen your skills as you focus on becoming a professional photographer.