I'm in year 13 and about to do my exam next week, I've been taught to go through a scenario like this:
1. define the law/Act/Offence e.g. murder is the unlawful killing of a human being with malice aforethought
2. identify if the D had the actus reus (explain the actions of the D and why he has the AR)
3. identify the mens rea - oblique, direct, recklessness
4. identify any causation issues e.g. intervening act, factual causation
5. Identify any defences that could be used
6. discuss whether or not you think the defendant would be liable
Obviously, support with cases throughout and try to make sure that the cases match the scenario so for example, don't use a case that was found guilty of murder if the defendant in your scenario is innocent. This structure could change depending on the point of law, for example, in unlawful act manslaughter there are rules to determine whether the defendant is guilty - in that case, use the rules of the offence but also consider MR/AR/Causation.
Hopefully, this makes sense!