Probably the most trouble-free, easy way is to run a cylinder balance test. If you have a code reader, all you do is run the KOER test, then when its done, blip the throttle, and it should start revving by itself and whatnot. It shuts down one injector at a time and looks for differences in RPM. If you have a dead or badly clogged injector, there should not be a large drop in rpm on that cylinder. Then, it'll tell you which cylinder(s) is/are the culprit.
If you run this test several times, and it comes out good every time, chances are your injectors are fine.
You could also probably tell from taking a peek at the plug (comparing it to a couple of others).
I'd do the same CBT as 1TMF noted. To hit the other side of his correct sentiments (that if it passes, you should be ok):
Just remember that if the test comes up with a weak cylinder, it's not an indication that the injector is bad! It's just lets you know that this cylinder has an issue that needs diagnosis.
Old fashioned shade tree mechanic trick- fire up the car, let it run for a minute until the headers just get hot. Dampen a paper towel and touch each header with the damp towel. If it sizzles the cylinder is firing and getting fuel and spark, if not, it isn't.