Why when I try to turn my car on it doesn't start unless I do it a couple of times?

I have a 1990 honda civic si and when i try to turn it on, turn the ignition key all the way, the engine doesnt start. I have to do this a couple of times before it turns on. Just did a tune up (spark, wires, pcv, fuel filter, oil change, etc). What could be the problem?