You have to solve a few words before you start moving any pieces to try to maximize the number of double-green swaps. Any time you figure out a double-green, go ahead and do it - it will never keep you from getting the full 5 stars.
A trick is: if there is only one of a letter on the board, you can always put it in place without worrying about a double-green swap. Often times it opens up a chance for a double-green later.
You have to solve a few words before you start moving any pieces to try to maximize the number of double-green swaps. Any time you figure out a double-green, go ahead and do it - it will never keep you from getting the full 5 stars.
A trick is: if there is only one of a letter on the board, you can always put it in place without worrying about a double-green swap. Often times it opens up a chance for a double-green later.
Hope that helps.