So, hunting spiders like jumping spiders, wolf spiders, funnel weavers, and ground spiders, if they are only outside, might best be left alone. They are essentially harmless to people but are voracious predators. Orb weavers that build their large, beautiful webs in the garden but never indoors should be enjoyed for their architecture and beauty. They really aren't going to hurt anyone either. So, what I am saying is that we, as professionals who are interested in improving the home environment but minimizing the use of pesticides, should make the effort to educate the homeowner so they too recognize that having certain kinds of bugs around their property is appropriate and of benefit to their gardens. This isn't going to work for all of them, because too many people figure the only good bug is a dead bug, but at least we should take the time to try. 

When an occasional spider is found indoors I really believe that a vacuum cleaner is the best tool, and the homeowner can easily fire it up and remove that offending critter. I am realistic enough to know that in the mind of the regular customer of yours their feeling is that they are paying YOU to keep them from ever having to see a live bug in their house, so one spider will result in a call to YOU to come out and take care of it. Perhaps this can be minimized by setting the expectations right up front when you take on the account, perhaps it cannot. I just don't see the benefit of spraying thoroughly throughout a home on the inside in the hope of killing the single marauding spider before the customer sees it when 1 minute with a vacuum cleaner does the job better and faster. 

On the exterior I fell in love with the Synthetic Pyrethroids when they first became available for spider control, and they still work great. But, many of them are going to last only a couple of weeks before they degrade to a point that they may not kill the spider that passes over the treated surface. Anything you can do to treat directly onto surfaces where the spiders spend some time will help. There are longer lasting insecticides, such as the microencapsulated formulations and possibly new formulations like Suspend Polyzone that claims to last up to 3 months outdoors. But, pyrethroids have good labeling and work very quickly on spiders and other arachnids. Be aware of the new label restrictions for outdoor uses, but you still can treat broad surfaces on the undersides of eaves as well as 3 feet up along the foundation and into any cracks or crevices. 

Non-chemically you should make some suggestions to the customer based on your initial INSPECTION of the property. If they have a spider problem there must be some reasons, and these reasons generally are that there are plenty of insects to eat and plenty of places to hide, for hunting spiders. Often it is exterior lights that draw the moths and other night-flying bugs, and spiders figure this out and hang out by the lights. These can be turned off at night or bulbs changed to yellow, which is less attractive to insects at night. There may be rubbish or firewood or other piles of things stacked against the outside of the house, and these should be removed or stacked away from the foundation. Any trees or shrubs growing against the exterior walls need to be trimmed away to remove pathways. Thick vegetation near the foundation should be trimmed up off the soil and as much as possible a 2 or 3 foot wide strip of bare soil maintained around the exterior foundation. 

There are several spider web removal products that also claim to discourage web building spiders by making it difficult for them to attach their webs to the walls, so these can be used. You should remove webs outside with a cobweb duster on a routine basis, as the presence of the webs, even if the spiders are no longer alive, creates the impression with the customer that they still have spiders. On the inside webs should be removed with a vacuum to prevent smearing them on the wall. 

So, a variety of thoughts, and hopefully this is helpful.