You must conduct a direct examination for YOUR witnesses. Direct examination means that you must ask your witnesses questions in a non-leading manner.
Non-leading questions are questions which can be answered by stating a fact, rather than answering "yes" or no". Your questions should call for one key fact at a time. It is also best to ask a series of questions leading up to the crucial fact of the case. When you reach that point, simply ask your witness "what happened next?" or something similar. Your witness will be more believable if he/she is to explain important events in his/her own words.
Example of a non-leading question:
"Tell me in your own words what you and I did to clean my apartment?" "What cleaning materials did we use?" "What happened next?"
If you ask your witness questions that require a "yes" or "no" answer, you are probably asking leading questions, and the hearing's officer may stop you. Leading questions are not allowed on direct examination.
If a friendly witness doesn't testify in the same words you would use, don't ask him to change his testimony - unless he made an obvious misstatement which can be easily corrected. Asking your witness to change his/her testimony usually causes confusion, and makes him/her repeat the part you are unhappy with.