I'd start by making sure you know the relevant intent standards for each crime: malice, specific, general, or statutory. That's probably the best way to determine in most hypos whether criminal liability attaches.
Malice: murder, arson
General: battery, rape
Specific: almost everything else
Statutory: because the law says so (statutory rape, selling alcohol to minors).
That's how I'd go about it, because the intent standard determines whether one must consciously intend to do the crime, if the act of doing it itself imputes intent, if gross recklessness qualifies, or if intent or knowledge is irrelevant to liability (statutory). Also, the intent standards determine whether any mistake of fact absolves liability, only reasonable mistakes absolve liability, or if no mistake absolves liability.