I agree, being comfortable with yourself is the most important thing you can do. In my experience the more worried I am the worse I stutter, so if you go around constantly worried about what people think you'll stutter even worse. I also have frequent trouble with beginning sounds, and one thing I like to do is try to change my words. If I have trouble with one word, I'll switch to a synonym that gets my point across but is easier to say. Wen that's not an option (like when I have to say my name) I take a deep breath and then say it on the exhale. Or I put words in front of it, like "hey there I'm blah blah blah" instead of just saying "I'm blah blah blah." But sometimes not even that works. In those cases, I just try not to rush myself - cause that only makes it worse - and deal with my inability to speak for a couple of seconds. The word will always come out eventually, sometimes it just takes some time. And it's awkward and weird, but preferable to repeating the same sound over and over again. I've found people are generally willing to wait.