How do you help a person who lies about almost everything?

You wont be able to stop this happening,that has to come from the person herself.Who knows why people do this,to make themselves seen in a better light no doubt,whatever the reason,I reckon you would be wasting your time trying to stop it.

Hmmmm.... a very interesting question! I think you should make that person realize the bad effects of this habit, like do it with him/her once or twice so it would hurt a little so that he/she gets the point.

I honestly don't know how you can stop a person from lying because I think lying is in their own hands and they choose to say it so they can stop whenever they want IF they want to.

There is nothing you can do to get this person to stop lying. I have a person who lies to us all the time and we ended up not believing a word she says. We have called her on serval occassions and she still continues to lie. I would just distance myself away from this person. Have you talked to her?

make them deal wiht the consequences of their acts. Tell them you are tired of it, can't trust them for the truth and can't have a relationship wiht a person you can't trust. Then leave them in the dust. They will, hopefully, learn from this and not do it to the next friend they make then.
Tough love is the only way, sometimes? (They'll be mad at first. Stick to your guns and let the relationship go. YOU also have the right to be wiht trustworthy people.)