To have your photo look really sharp, even if you have a shallow Depth of Field, you need to select the point where you focus, with care. It must be on the point where you look when you look at an image. This makes the viewer see your subject and then if you have the right composition, follow your visual lines around the image.
Even in a landscape you must focus on something. Landscapes have foregrounds, mid areas and backgrounds. Select your point of focus on something in the foreground or middle area (usually). Remember, where you focus, is where your eye goes to first when you view an image - even if it has a large Depth of Field.
Creatures with eyes are easy - you focus on the eyes. However, this can be a problem if the creature has a long nose eg. a sheep or if the bird has a tiny head and large chest and wing area. What do you do? You try and arrange yourself & camera at an angle to the subject that has the minimum distance between the eye and the nose. In other words you take the shot with the head partly side on and have a mid to large Depth of Field. If you have to have a small Depth of Field, then you need to have the eye and shoulder or nose on the same plane.
Easy - right! Try doing that with a wild animal. Its patience and luck!