A competent inspector should know enough to understand that there is almost always a small possibility that an inspection could, no matter how thorough or competently done, miss some termites.

There are several reasons for this:

Lets say you live in a known risk area for termites (count the advertisements in the telephone directory).  It is normal for an inspection to be recommended to be done not less than once a year.  Some people tend to stretch that out a bit.  If you do go for less-frequent inspections it will almost certainly impact on any insurance or warranty you may have covering the termite risks.  Read the contracts.

Here's some pointers to get you started.

You can do things that reduce the amount of water getting in to the soil near your perimeter walls:

1. Make sure that rainwater on the roof does not drain into the soil.
2. Grade the soil around the house so that water drains away, not towards the walls
3. Don't have gardens, ponds, sprinklers, ferneries or pools near walls.
4. Make sure that overflow drains from hot water services and air conditioners don't soak into the soil near the wall.

You can do things to help the water get away: 

All pests, like us essentially seek the same basic things: food, shelter and water to drink.  Without good supplies of these they can't thrive.

This will depend on the size and complexity of the structure, the location and the type of inspection required.  Say you are getting a typical house checked out before you buy it.  I would normally expect that to take around two to three hours for the pre-purchase inspection.  Obviously, an old or heavily renovated house will take more effort than a brand new one.  If you have a contracted service or have a barrier system installed (subterreanean termites), then the regular inspection can be a lot faster, maybe even 45 minutes to one hour.  If you have reported an i