Regular inspections of the exterior and interior of your house are one of the best ways to protect your investment and avoid costly repairs. Basic home inspections can be done by homeowners themselves and don't take very long to complete. Inspections should be done at least twice a year, once in winter and once in summer.
The summer inspection should be done early in the day to avoid the heat of the afternoon when pest insects may go into hiding. Slowly walk around the exterior. Look for evidence of insect activity on the siding and especially the area where the siding overlaps the foundation. If you find large ants "trailing" into or out of the house capture a few for identification. Also check under the house, if possible, for termite and powderpost beetle activity.
Anyone who has watched the TV show "This Old House" knows that water damage is far more important than insect damage in most situations. Winter is the best time to inspect for water and moisture problems. Again, walk slowly around the structure and look for water wicking up the foundation from saturated soil. Overflowing gutters are another source of water damage. Also, check structural wood for evidence of dry rot and mold damage (this can be done during the summer inspection as well).
Keep notes from all your inspections so you'll have a record of when the last inspection was done and what you found. See the home inspection pages at 'Bugs for more information and a form to help with keeping records.