Spiders like things they can hide in and under. Fewer places for hiding make it harder for spiders to eke out a living at your property.
Inspect the inside of your home often:
Spiders are drawn toward areas of low traffic. Making a point to regularly clean/dust all parts of your dwelling will reduce areas of comfort for spiders to settle in.
Inspect the exterior regularly:
Most spider problems begin on the exterior of your home/business. Inspecting the exterior of the property will detect spider populations before they get a chance to expand further on the outside or spread into the structure. Reducing the amount of foliage close to your building will also remove harborage for pest insects.
Spiders are attracted to areas where there are moths and other flying/crawling insects or "food" hanging around. This might include outdoor security lights, water features, around windows/doors and gutters. If spiders are hanging around, you can change the type of window coverings to allow less light out of the home at night, or change the type of lighting inside or out to reduce food sources for spiders being attracted to your home and thus encouraging spiders. Warm LED bulbs are best for reducing insect numbers.