Over-using the word "then" as an action separator in my early writings was a big issue for me, and I'm still un-writing it from manuscripts when I catch myself doing it now. I'm not sure I've ever actually had the semi-colon fetish, but I've come close, and regularly find myself rewriting text in order to share the load between semi-colons, M-dashes, ellipses and the occasional set of parentheses.
I think over-using words probably should have been in that list. I'd also be tempted to add overuse of atypical sentence structures, which can be a nice personal signature when used occasionally and appropriately, but can be jarring and annoying when used too often.
(And I actually can't think of a good example right now... if I think of one later, I'll edit it in.)