Truth be told, I don't have any strategy as such when it comes to the free rolls.  I get five per day and allow them to bank up for a few days (not more than a week at a time - usually) as I'm not online as much as people might think.  When I do roll, it's interesting to see how few of one or the other prizes there are, or, conversely, how many of one prize or another there are each time.

If I win enough bitcoin from these banked rolls to buy another 100 FUN tokens, I do so and add to my 365 day investment.  (It'll be interesting in about eleven months time to see what people do with their FUN tokens)