Focus- One of the leading complaints about pictures is that they are not sharp. The degree that your picture is sharp and clear is directly connected to the quality of the picture. Focus is a combination of factors, Stillness, focus placement, and closeness to subject.
Extra bit- All screens show pictures with a resolution of 72-96 pixels per inch. NO matter how big a picture your camera says it takes, to view it on any screen you are looking at a greatly diminished version of it. A print pictures is typically 300 pixels per inch.
Stillness- The more still you can hold your camera or phone, the more in focus it will be. Bring your elbows to your sides and lock them in, then hold camera with both hands. Half press your shutter button, or tap in the screen of your phone to focus. Hold still as possible, and trigger the shot. It is harder to get in focus shots at night due to the lack of light.
Focus Placement- As much as possible place your focus point on an eye if you are shooting a person. As tempting as it is to put the focus point on the shirt, the sharpest pictures have the eyes in focus. Either tap on the eye on your phone or place the focus point on the eye if using a DSLR.
Extra bit- Read the camera manual, and know how to operate your camera, and practice in all modes.
Closeness to subject- Frame your shot and move two steps closer. Fill the frame with your subject. Far away shots show big pictures, is all of that vital to the story. Get closer and use the focus techniques, and you will be pleased with your results.