The number one trick I have is to never overthink, NEVER!!! Because overthinking at-least for me always causes me to stutter and I don’t know why. In my experience I would always have trouble ordering food at a drive through and if I’d overthink I’d stutter, BUT if I imagine myself already having the food in hand and ordering something I think is tasty upfront I’m throwing my brain/myself off guard so whatever I say after taking a deep breath comes out clear and concise. Very weird but its a mental game with me and my stutter