First, make sure your camera is off. Keep that in mind. By turning the camera off, there's no more power going to the sensor so there's no like electric charge going and then static could possibly draw dust in.
Point the camera down and then take the lens off and put it down. Take the lens cap from the new lens that you're goint to put it on, pop it onto the other one (Make sure your camera still facedown), and then lock the new lens onto the camera.
The reason it facing down because I don't want if anything get inside the camera.
If the wind is blowing, put your back to the wind and get the camera closer to you so there's no wind or dust that could possibly fly in.
So the simple quick tip is:
- Turn your camera off
- Hold the camera down
- If it's windy, put your back away and walk away from the wind