If you require to speak to the Fiscal regarding certain aspects of the case, the morning of trial is NOT usually the best time! Your case (especially if it is a summary trial) will more than likely be only one of a large number of cases which the Fiscal is dealing with that morning and Sheriffs generally do not welcome delays in commencing the court business. You should telephone the Fiscals office the afternoon before if it is a relatively simple point you wish to raise or well in advance if the matter is more complex, in order that any difficulties can be cleared up in time for trial.
Unless you are giving evidence as an "expert witness" you will not be present in court before being called to give evidence but will be shown to a witness room, along with the other witnesses in the case. After giving evidence, you must not discuss the case in any way with a person who may still be called to give evidence in the case. If you are not a potential witness in the case, there can be no objection to your presence in court - however make your status clear to the Fiscal.
It is entirely a matter for the Fiscal which witnesses are called. There is no obligation to call all the Crown witnesses in attendance. If the Fiscal feels that, for example, a particular point has been established in evidence, then any other witness who was to speak to that point is unlikely to be called to give evidence. Do not therefore be alarmed if you are not, in fact, called on the day of trial. Often on the day of trial defence agents will be more prepared to agree aspects of the Crown case, which is another reason why you may not be called to give evidence. The bar officer will usually advise you if that is the case.
In court you should address the Sheriff as "my lord" or "my lady", as appropriate, speak clearly and slowly, keeping an eye on the Sheriff's pen. If you do not fully understand a question say so, and do not seek to answer a question before the questioner has finished asking it! This advice applies when giving evidence-in-chief, as well as during cross examination. Bear in mind the purpose of cross-examination which is to weaken or destroy the opponent's case, and do not allow yourself to become obviously ruffled by aggressive defence cross-examination tactics. At all times be completely candid. If you do not know the answer to a question, do not attempt to guess, simply say so.
Contemporaneous notes made by you can be referred to in Court during the course of your evidence as an aide-memoire. You should be aware that the defence could ask to see the notes and question you as to the content, though this would be unusual. Ask permission before referring to your notes.
After giving evidence, you are usually free to leave if you wish or you can take a seat in the public gallery for the remainder of the case. If the case was investigated and reported by you, it may be appropriate for you to remain at court for the duration.
There are lessons to be learned from every case e.g. how to emphasise to the Fiscal the main points of a case, how to give evidence positively and persuasively, how to deal with cross-examination. Every case should therefore be regarded at least in part as a learning and training exercise. There is always the "if only" aspect to be borne in mind for future cases.