The only way to increase your chances of winning is to enter more combinations of numbers. It is possible, however, to choose combinations of numbers which, if they win, are likely to win more money by virtue of having been chosen by fewer people. For example, if you choose the numbers 1,2,3,4,5,6 - this combination has as good a chance of winning as any other, but it is likely that lots of people will have chosen these numbers too, so if you do win you have to share the prize with them.