Dust is the bane of most photographers existence. I spend many hours removing dust from my clients photographs that they have taken. Every now and then I do have dust on my own photographs as I take my camera outside often :p The best habit for anyone to be in is to learn how to change lenses correctly and to try to keep the dust to a minimum. When changing lenses on an SLR camera body, make sure to always keep the body opening facing forward and/or down. Never put your camera body down with the opening facing up! You are just asking for dust to enter if you do. Try to be as quick as possible when exchanging lenses so as to limit the air exposure time for both the lens and the body. Over time, one does get quicker and better at this step. If you are out in the desert and have to change lenses, try to do so in a calm, protected place. Sometimes even changing it inside your jacket works to protect things!
I edit photos that my clients have taken often. Here is an example of a photo that one of my client's took:
As you can see, there is a plethora of dust in this photograph. The spot healing brush works wonders to remove all the dust. Luckily in Lightroom these days, there is a great feature called Visualize Spots, where you can check it and the dust spots become visualized to make it easier to remove the dust!
This photograph took a lot of time to remove all of the spots, but the finished product is worth it for my client!
So remember, be cautious where you change your lenses, do it quickly and always check to see if you have dust after a shoot before you go out for another day and shoot some more. It is not enjoyable to get home after a trip and realize you have dust everywhere on every photo that you've taken! Also, have your sensor cleaned by a professional :)