The stake is probably the most widely used weapon on earth to kill vampires. It is a quick and easy way to dispose of the beasts. It is usually a sanded stick that is about 1- 1.5 feet long that is very sharp at the point. Almost every slayer carries one.
Garlic Juice is a very effective way to either kill or inure a vampire. Most to all vampires are highly allergic to it. If garlic juice gets on a vampires skin it can severely injure them. If they ingest it or it gets into a cut, it would most likely kill them. That is why it is so effective.
Holy Water/ Crucifix
It was thought by the Slayer Society that these tools were good to fight off vampires because Vampires hate sterling silver and they are also allergic to holy water. Both of these were proven false when Joss went to Bathory to try to exterminate Vladimir Tod.