Car will not start on first try?
You may have a leak - down in your fuel system. Then, if you switch the ignition key to start too quickly, there is no fuel pressure at the injectors.
Switch on the ignition but do not attempt to start for 10 seconds.
This will give the fuel pump time to get the fuel pressure up.
Switch off the key and then switch back on and try to start.
If it starts (and you say it usually does), I think you have proved leaky injector/s. You can try adding an injector cleaner to your fuel.
If that doesn't fix it, then check the fuel pressure at the fuel rail on the engine. Check the pressure while running and then watch for pressure lose after engine shut down. The pressure should not lose much. If it drops to almost zero, you will need to find and fix the leak down.