The rule of thumb is to add half the gust factor while on the approach. For example, winds at 15 gusting to 25 provides a gust factor of 10 knots, so add half that, or five knots, to your normal approach speed. Some pilots have difficulty dividing by two when in a crosswind so they add in the full gust factor plus some extra just to be sure. Then you can be confident that the landing will be entertaining. Do not expect to achieve the book numbers for a short-field landing during a strong, gusty crosswind.
Shear occurs when the wind changes direction, speed, or both within a very short distance.
It can cause an aircraft to stop flying. Although we normally think of shear near thunderstorms, it can be serious on a gusty day, depending on wind strength and terrain surrounding the airport. Then it depends on how quickly the aircraft reacts. We'll spend more time on this in a future column. If it's a serious encounter, go around and perhaps look for someplace else to land.