the first thing to do is to learn to identify the dangerous spiders in your area. do not depend on folklore or information from local people. Go to the library or search on line for "Dangerous Spiders (type in where you live).
For example here is a listing for Dangerous spiders in the UK.
"If we could charge a pound for every question we receive about "giant, deadly, poisonous, man-eating, black widow spiders" we could retire today.
If you've found one of these "giant, deadly, poisonous, man-eating black widow spiders" then don't worry. Even though some spiders can, and very occasionally do, bite. It's very unlikely the spiders around your house are venomous to you or your pets. Although spiders use venom to overpower their prey, there are only a few spiders which have fangs strong enough to pierce human skin. If there are venomous spiders in your area, you will probably hear about them from your friends and neighbours.
ONES TO AVOID
Despite the fact that we have no dangerous spiders in UK, they seem to strike fear into people more than any other creature. We wanted to find out if any of this fear was justified, so to get an expert opinion we contacted Ian Dawson from the British Arachnological Society and asked him if there are any spiders in the U.K. which people should be wary of. Here's what he told us...
Garden Spiders (Araneus diadematus) have been recorded biting occasionally causing inflammation and itching for a day or two, and it is probable that a few other large spiders such as Argiope have jaws which can pierce human skin - though I have in fact never heard a convincing report of Argiope biting.
One interesting case is Tegenaria agrestis, a spider native to Europe (including southern Britain) which has been introduced to the U.S.A. where it is known as the Hobo Spider and has a bad reputation for giving nasty bites. To the best of my knowledge it has never been recorded biting in Europe, so the only plausible explanation I have read is that a different genotype has arisen over there. The large hairy spiders which turn up in the bathtub are also members of the genus Tegenaria, several species of which occur commonly in houses, but none posing the slightest threat.
The only species which has a bad reputation is the False Widow which occurs in association with human habitation in most parts of southern England and has been implicated in having a bite bad enough to need medical attention. However, it is certainly not life-threatening and the few bad bites may be more a case of someone reacting badly, just as some people are allergic to wasp stings. It can be very abundant where it occurs, such as in Portsmouth, and yet we never hear of it causing problems. Certainly none of our few spiders that have been recorded biting are at all aggressive, so any bites are accidental."
Source:
http://www.uksafari.com/spiders4.htm