Although the problem is the same, different models have different specifics if the main relay is bad. On an Accord, you will lose fuel pressure. If it's bad on a Civic, you will lose power to the injectors and the fuel pump but you may not lose fuel pressure because the injectors can't open without power. When the main relay goes bad and there isn't any voltage at the injectors, it will set a code 16 for an injector because the computer doesn't read voltage on the ground side of the injector.
Before you dive in too fast, it's also possible that the car has more than one thing causing a hard start. You could also have a bad ignition switch, a bad igniter or a bad ignition coil. To test for spark, you should first perform a simple spark test, then you can test the coil itself. Unfortunately to test the igniter itself, you need an automotive oscilloscope, something you won't really need too much in a home shop.
The main relay will give you the same symptoms as a bad coil or a bad igniter. A main relay usually only fails when the weather is really hot. You might have a hard start every now and then, but not enough to really cause you any concern, but when an igniter or a coil fails, the car won't start at all until it cools down.
If you've determined that the culprit could be the main relay, you should do a Honda Main Relay Test to be sure. There's nothing worse than replacing an expensive electrical part only to find that it wasn't the problem in the first place. Don't forget, many parts suppliers have a "no returns" policy on anything electronic.