Use Autofocus

your camera's built-in autofocus can usually do a much better job than you can (especially if your eyes are - let's say: older).

read your camera's manual, and learn how to control where it will focus. this usually involves a focus point: a dot in the viewfinder which shows exactly where on the image the camera will try to focus. on most cameras, you can point the selected focus point at the subject, hold the shutter release button half way down, then recompose the image while the camera will not refocus.

this means you don't have to focus and compose at the same time. you can focus, then compose, then take the shot.