Hi Tony! There is a very helpful thread by Valerie which states it's all basically just chance, however, if you do your clicking at about the same time of day, every day, it increases your chances of winning.
edited to add - Here is the link to that thread: How to win in ClixGridhttp://www.clixsense.com/en/Forum/111814/How_To_Win_in_ClixGrid_The_Secret_and_Hint