you can try a few things, as said, spark plugs/gap, ht leads, coil pack, etc etc but it all costs money and may not solve it. advantage of goign to a specialist is they can try a few things to see if it solves the problem.
The other issue with misfire codes is they might not actualy be misfire, might be a default code its used. My dads kept getting missfire on cylinder 3, turned out to be something rather more sinister