I've always used substitute words where possible. And a variety of tics and tricks when it's unavoidable. But, sad to say, sometimes I've just avoided the situation entirely. ("God would look at that, I've only gone and fallen down the bloody stairs!") The older I get, and the more things I open myself up to, the more I work on the other parts of my personality, the more confident I get. And then I don't care if I stutter.