I'm not autistic, but I have tics.
'Normal' stimming such as shaking my legs and other excess fidgeting helps to reduce their frequency, so I presume autistic stimming would yield a similar result. I also have weirder things I do like making stupid noises etc. on purpose to 'entertain' myself, and that seems to ease tics and mental de-railing.
I don't know of any other methods, except to force myself to not tic for long periods of time, which reduces them until I begin to notice that I haven't ticced for ages, and then it usually starts again.
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Unapologetically, Norny.
-chronically drunk