I'm not sure if I would. I don't think the government's worth overthrowing at the moment. I'd rather be democratically elected and so have the support of the people (it'd make my bid for world domination a little easier if it was popular).
But if I had to, absolute control of the military and legality would be paramount. When you have a monopoly on force, it means less resistance. Exploiting legal loopholes would mean you don't rely entirely on the military for your claim to power (you don't want the army to feel that they can replace you). But as said, securing popular support would be my first goal.