This one is more like a 3 minute quick tip...
It's understandable why we photographers are so apprehensive to change lenses in the field. I mean we've paid an arm and a leg for our gear!
However, we needn't be scared providing we're a little smart about it.
Firstly, don't even consider changing lenses in dusty conditions. Dust will be the death of your camera!
Secondly, stand with your back to the wind. Your body literally blocking the wind. This will prevent anything being blown into your sensor.
Thirdly, hold your camera body vertical with the mount facing the floor. Gravity will do it's thing.
Obviously the more you change lenses, the higher the risk of getting a dirty sensor. It shouldn't stop you though, just use your brain and take preventative measures.
If the unthinkable happens, go get the sensor cleaned professionally. Having a DIY session yourself can cause irreparable damage. We really don't want that!