When cleaning a home's siding, work from the bottom up when applying the cleaner and from the top down when rinsing to avoid streaks. For the tougher spots use a scrubber.
Siding is notorious for soaking up mold and mildew. Cleaning it properly every summer can keep them away, help prevent staining or etching, and keep the siding looking brand new.
Crawlspaces with dirt floors are tremendous sources of moisture. The surface might appear dry but most often moist earth isn't too far below. Moisture in a crawlspace affects not only the flooring right above it but can affect the entire house.
It is a good idea to buy a vapor barrier if one is not already in place. A vapor barrier can be made out of a variety of materials from foil to plastic. It acts as a physical shield against moisture.
Check for signs of termites in the crawlspace.
If you have exposed piping in an unheated crawlspace, use pipe wrap.
Another thing to check for is sewer lines. Check for leaks under where the toilet sits.
Summertime is a good time to go into the crawlspace because it stays cool even on hot days. It is essential to check the crawlspace at least once a year to make sure it is free of pests and to check that the vapor barrier is in tact and doing its job.