Use the numbers from a fortune cookie and hope for the best. Perhaps choose numbers with numerology, say a chant or make a charm for luck or wealth you use while purchasing the ticket. Ultimately it's random, so have a back-up plan like a job and a high interest savings account.
While there are such things as good luck spells, you need to realize just how unlikely winning the lottery is to begin with. Depending on which lottery it is that you're trying to win, the odds are usually somewhere near or worse than one in one hundred and fifty million . The odds of being struck by lightening, as totally unlikely as that is, still manages to be about a hundred and fifty times more likely (one in a million).
A luck spell to help you win the lotto is like trying to shrink the ocean by scooping out buckets of water. Truly, it would just be more reasonable to use a general money-drawing ritual. It won't draw you millions of dollars, but it's likely to actually succeed at drawing money, which a lottery spell just isn't.