There are a few things to do to when trying to diagnose a misfire. All vehicles are different, but there are a few places to start.
1)If possible use an OBDII scanner on newer vehicles. The misfire counter function can help you determine which cylinder is behaving badly. Clearly this is not an option for all people and vehicles though.

Note)Even without engine scanners you can identify which cylinder is causing a dead misfire. Carefully disconnect one spark plug at a time. If the...