Assuming your pistol is able to dry fire, take up your normal stance any distance from a light coloured wall, close your eyes and bring your pistol up to aim.

Open your eyes and check foresight alignment in rearsight notch.

If OK, squeeze trigger as normal and, as in previous reply, check for movement at point of trigger release.

Remember to follow through.

This is a good excercise to check that your trigger finger is moving back through the axis of the pistol and not deflecting left or right or up and down.

Hope this helps.
ATB
Mike.