1997 Subaru Impreza Error message that my #4 cylinder Is mi

I tested my car with an Actron cp9125. The code I got back was P0304. The computer said that code # means my #4 cylinder Is misfireing. My question to you Is ,do you have any sugestions on how to troubleshoot the problem or possibly fix the problen? Thank You Very Much!!!!! A very happy subaru owner. Could please send an E-mail back to me to....steelermania7@verizon.