If you are interested in the street photography you already know basic techniques of focusing
- Hyperfocal distance
- Zone focusing
There is no reason for me to explain concepts of Depth of Field (DOF) and hyperfocal distance in this topic. Internet and many books have plenty of useful information in any level of details.
When I use my Point&Shoot camera (Canon S90) most of the time there is no need to be concerned about focusing. This camera has such deep DOF that only very special circumstances make me think about changing my focus settings. Effectively, Point&Shoot always has hyperfocal distance or very close to it.
I don’t use hyperfocal distance with my DSLR camera unless my composition demands focus to infinity. Control of DOF with selective focusing is the basic method in the photography to direct viewer attention. As another big bonus, large aperture allows using fast shutter.
I use combination of zone focusing and autofocus. Before I make the shot, camera is always prefocused for predicted distance. If I decide to use viewfinder there is always option to use autofocus (with separate AF button). Modern lenses with quick shift make this mode of operation very convenient. My older favorites don’t have quick shift so I prefocus them pointing to some boring object. To use autofocus photographer has to understand its intricacies and limitations. Don’t focus by pointing to the smooth wall and, probably, forget about autofocus when it is dark or other special conditions. Many photographic sights are the great source of information about autofocus.
Don’t settle on one-fits-all rule. Find your own style to take your best pictures.