There's no perfect solution for every situation because this can't be a quick fix. In the shitty situations with strangers where you feel you can't just stop and take all the time you need, you're just going to have to work through it. But you can still give yourself goals. Goals like holding eye contact, saying everything you want to say, not switching words, or even the goal of letting yourself feel uncomfortable and trying to be a little more ok with it. The most important thing is that you choose something you know you can do. It really is about baby steps and adding them up, not moving up, crashing down, and repeating cycle. Disclaimer: you will still have periods up and down, but you want to zoom out and see that wavy line overall moving up as you struggle less as you expand your comfort/ability.