According to John Von Neumann's game theory, the best strategy for lottery is not to buy lottery. That maximizes your expected winnings, because it makes them zero, and with any other strategy they will be smaller than zero.
I know this isn't anything new, but it seems that some people just aren't able to understand that lottery is not a fair game. Another thing I usually tell them is: "I don't spend any money on the lottery and I get almost the same winning probability as you". But usually it doesn't work.
Lottery has always intrigued me. People play because they can "feel" the big money they could get but they cannot "feel" the small probability, for most people is not used to handle small real numbers. But I always wonder if a "reverse lotery" would also be successful: instead of paying for a ticket you get paid for getting it, and if you "win" you have to pay a couple of millions, or you get a debt for the rest of your life. If you take into account that most people don't use long-term thinking too much, maybe they would also play (you get short-term money for a long-term losing probability). What would be stronger, greed or fear?
Jorge Luis Borges writes about something like this in one of his "Fictions": a city in which lottery completely controls people's lives, it decides who is the governor or who must die. Quite surreal, but interesting.