A common approach is to make the technical side as forgiving as possible. A normal-to-wide lens is easiest to aim discreetly; around 35mm is a popular choice. Stopping down to about f/8 gives more depth of field, so slight focus errors are less noticeable.

Manual focus can work very well if your lens has a distance scale: pre-focus to an expected working distance and rely on the extra depth of field. That’s one reason small cameras and rangefinder-style setups are often associated with this technique.

Autofocus can also work, especially if you take several frames and slightly recompose between shots. Some photographers use broader AF area selection to improve the odds of a usable frame.

Shutter speed depends on the look you want. If you want crisp results, use a faster speed; slower speeds such as roughly 1/15 to 1/60 can add motion and energy, but they increase blur risk.

For staying unobtrusive, keep your movements natural and don’t make the camera-handling look deliberate. Practice first on static subjects so you learn how your framing and focus behave without bringing the camera to your eye.