Before you sign the check over, you need to make sure that the bank allows it. Sometimes bank's do not allow it. If they do, usually the person who the check is signed over to must have the amount of the check in his or her account. This is to cover check should it bounce.
Sign the check on the back where you would normally endorse it for cashing or deposit. Below your signature, write "Pay to the Order of:" and write the person's name that you are signing the check over to.
Have the person you are signing the check over to sign below your signature and the "Pay to the Order of." This should be done at the bank, after you have received clearance from the bank professionals to sign the check over.
Cash or deposit the check.