1997 Honda Civic Misfire on cylinder 1 and code P1399

I have a 1997 honda civic. About a year ago it started misfiring and running rough. Before I took it to a mechanic I replaced the spark plugs. It ran fine for quite a few months after that and recently started to do it again. I had someone pull the codes for the check engine light and the result was a code p1399 and Cylinder misfire detected on Cylinder 1. With the probable causes being 1. Ignition system fault spark plugs 2. Vacuum leak 3. Injector Fault 4. High or low fuel pressure. How should I proceed to trouble shoot based off of my past experience of replacing the spark plugs and it working. I plan to do that but it seems that it is unusual for plugs to go bad in less than a year. My next thought would be that I jiggled a bad wire that started working when I replaced the spark plug. If I replace the spark plugs and it still misfires should I replace the spark plug wires. What other suggestions would you have in trouble shooting if those options did not work.