To get a larger share of a big jackpot simply buy several dollars worth of the same number!

To get all of a big jackpot get one ticket with some combination of numbers that is perceived to be especially unlikely to win, e.g. 1, 2, 3, 4, 5, 6. The odds are exactly the same as the odds of, say, 12, 25, 31, 35, 42, 48 but no one else is likely to pick such a combination because it is perceived as being particularly unlikely.