Cross examination is asking questions to your opponent's witnesses. On cross, you are allowed to ask leading questions. Leading questions suggest the answer in the question itself. It usually has a yes or no answer.
An example of a permissible leading question is:
"You stated that the apartment was as clean as possible yet you still will not return Joe's security deposit, isn't that true?"
Don't submit evidence against yourself or ask questions which may weaken your case. Don't ask follow-up questions like: "In other words, Mr. Witness, are you saying that..."
The first rule of cross examining an unfriendly witness is: if you don't know what to ask, don't ask. Don't ask an unfriendly witness to repeat his testimony - he is unlikely to say anything that will help your case.
Remember! Don't argue with any witness over his previous testimony or highlight what the witness already said against you.