Question: What should I tell someone who's considering being my guarantor?
Answer: You should tell a potential guarantor that you need someone else to sign the lease in order to rent the apartment you want. The guarantor should be available to sign your lease, and she should understand that she's on the hook for your rent if you can't pay it. You should also let the guarantor know she'll need to sign the lease again if you renew it (assuming you still need a guarantor at that point). Most of all, you should thank any person who agrees to be your guarantor, since they're taking a financial risk for you.

