Dust and grit inside your camera can wreak havoc with the shutter, film transport mechanisms, and the like. If you possibly can, do your film changes in the car or with the trunk open and working where you re at least protected from the direct assault of the wind and blowing sand. It s also a good idea to have a can of compressed air or a similar product with you. These do wonders for getting dust and grit out of the nooks and crannies of the outside of your camera body. Be very careful if you use such products to dust off slides or negatives for scanning at home.
Rainy days are a bit more of a challenge.
Modern cameras are pretty rugged and will withstand a lot of abuse. That said, however, you won t want to take a good camera out in a gale unprotected. Cheap protection is as near and cheap as a box of 1 or 2 gallon plastic bags with a zip seal at the nearest grocery store. You want to be able to zip the bag shut when you don t need access to the controls or viewfinder to protect the camera. Slit the front of the bag for the lens to go through the bottom and seal the bag around the barrel of the lens hood using a big rubber band.