The answer to 'how to prevent spider' is to take a multi-pronged approach to eliminate entry points, reduce attractants, and use targeted treatments. First, seal any cracks, crevices, and other potential entry points around your home using caulk or other sealants. This will help prevent spiders from getting inside. Next, remove any sources of food, water, and shelter that may be attracting spiders, such as clutter, standing water, and overgrown vegetation. Finally, use targeted spider-specific insecticides or natural repellents in areas where spiders are commonly seen. Reapply these treatments every few months to maintain protection.
If you have a serious spider infestation or are dealing with dangerous spider species like black widows or brown recluses, it's best to call a professional pest control technician who can properly identify the problem and apply the right treatments.