There's no simple cure and anything you do find that works immediately well may not last. As paradoxical as it may be, I would suggest you stop focusing on whatever sounds make you stutter. You probably don't stutter on them midsentence because you're not focusing on them as much, whereas you almost certainly are at the beginning of them. Let it be. As cheesy as that may sound, stuttering isn't something that can permanently go away if you try to directly fight it. Let the words choose themselves, and don't focus on the outcome.