When people choose to buy lottery tickets, they use all kinds of strategies to pick their numbers. Of course everybody knows that a lot of luck is needed to win big at the lottery, but who wouldn't like to improve their odds a little bit? Eliminating improbable combinations like 6-7-8-9-10-11 is not a bad idea, although technically such a set of numbers is just as likely to be drawn as is any other.
There is nothing wrong with having lucky number, like birthdates, anniversary dates etc. Or, you take a notepad with you on your way to work and just write down the first five or six numbers you see on street signs, billboards and so on.
But at the end of the day, the only strategy that makes sense mathematically is to pay as little as possible for your ticket, and at the same time have the highest expectation of winning at the lottery you picked. The chances of having 5 or 6 correct numbers are easy to find - most lottery websites actually give you the info about those odds. But winning expectation means something else: how much money can you expect to win per $ invested?
This expectation, obviously, does not depend on the odds alone - the amount you can win is equally important. Meaning that, assuming the odds and the ticket prices are equal, it is the amount you can win that counts, especially the size of the lottery jackpot at that time.
That said, it makes perfect sense to wait for a bigger jackpot before you spend money on tickets. That is also the explanation why it has become increasingly popular to play international lotteries. With lotto ticket courier services available online, lotto players are now in a position to buy any lotto ticket online, even lotteries that previously were unavailable to them.