What to do to prevent/get-rid of snakes?
The best advice I can give is to do some research on the type of snake it is.  Is it native? Is it venomous?  What does it eat?  Where does it like to live?  And then you get rid of the types of things it likes to live around.  Most snakes that live around people are harmless and pose no risk to health or property.  Usually they are doing quite a bit of good by eating garden pests like bugs and slugs.  

That said, getting a cat is usually a good way to keep small animals away, unfortunately, they keep the native birds away too.