Every company has a different modus operandi, but there are some general hints which will help you to solve a murder mystery.
In our events the detective will ask you for three things; method, motive and murderer or murderers - yes, there can be more than one! The method is how it was done and the more information you can give the better. For example we will not just want to hear that it was poison, but which poison and how it was administered. For this to be fair the answer must be somewhere in the clues, so look out for those details.
A good way to think about it is to question why everything exists. Why are those words used? Why is this place mentioned? Why did the suspect say that thing?
Sherlock Holmes is famously associated with deduction, but actually he followed a process of abductive reasoning before he reached the stage of deductive reasoning. Abductive reasoning is essentially forming a conclusion from the known information.
'Once you eliminate the impossible whatever remains, no matter how improbable, must be the truth' - Arthur Conan Doyle.
Motive and opportunity
The murderer should have a motive. You can remove those people from the list of suspects who do not have a motive, or whose motive is not strong enough for such a serious crime. Many people make the mistake of being suspicious of people who are named but only have a small role in the story, for example witnesses on a legal document. In the interests of fairness in any case the murderer's motive should be evident and not hidden.
Opportunity to commit the crime is also key. Who had access to the place where the person was murdered? Who had access to the person themselves? For example, if a person is murdered by a stranger there will be clues at the crime scene and in the position of the body. Ask the detective if they think that the killer was known to the victim based on what they have seen. Alibis must be checked, and thought given to whether they could be faked.
In each case there will be red herrings and part of the abductive reasoning process is to eliminate these based on the known evidence and not on conjecture. The process of a murder mystery should be fair. When the solution is revealed it needs to be acceptable to those who have invested their time in the game. Try to avoid giving too much weight to convenient solutions. As an example 'The Returning Twin' nearly always makes people think that the victim was the twin of the real victim. It seems to make some sort of satisfactory sense to people, and there have been so many examples of it in film and literature, that people will throw out a perfectly reasoned solution in its favour.
The best advice is to narrow down all of the information given through abductive reasoning and to follow the facts. Good luck, and have fun!